Issue：
Sometimes vxlan port with remote_ip set to the node itself was created when adding new L2GW Node to Open vSwitch HWVTEP Emulator.

Additional Info：
This issue was found while we executing HWVTEP Emulator HA node addition. But not sure whether it's related to HA node addition or not.
Once this issue happened in l2gw connection creation, it will happen every time even deleted the created l2gw connection to create a new one.
But by creating a new virtual network to create a new l2gw connection, the result may changes.

Environment details:
OpenStack Version：stable/ocata
ODL Version：Carbon-FR + patch
patch: https://git.opendaylight.org/gerrit/#/c/56773/
https://git.opendaylight.org/gerrit/#/c/56710/
https://git.opendaylight.org/gerrit/#/c/58787/
https://git.opendaylight.org/gerrit/#/c/59598/
HWVTEP: Open vSwitch 2.6.1 HWVTEP Emulator
: HA Cluster

What we did (Steps):
1. Create a L2GW Node with Open vSwitch HWVTEP Emulator
Set 'other_config:ha_enabled=true' and 'other_config:ha_id=0123456789' when creating.
2. Create gateway and connection
Confirmed the communication via L2GW Node was OK
3. Create a new L2GW Node with Open vSwitch HWVTEP Emulator
Create a HA Cluster with node created in step1
Set 'other_config:ha_enabled=true', and 'other_config:ha_id=0123456789'
VTEP and MAC were also set to the same vaule of the first node

Below are ovs information:
------------------------------
When this issue not occurred:
------------------------------

Bridge "ocata-l2gw1_vtep_ls1"
Port "vx1"
Interface "vx1"
type: vxlan
options:

{key="100", remote_ip="10.0.0.10"}

Port "ocata-l2gw1_vtep_ls1"
Interface "ocata-l2gw1_vtep_ls1"
type: internal
Port "2222-patch-vlan-l"
Interface "2222-patch-vlan-l"
type: patch
options:

{peer="2222-patch-vlan-p"}

Mcast_Macs_Local table
MAC _uuid ipaddr locator_set logical_switch
----------- ------------------------------------ ------ ------------------------------------ ------------------------------------
unknown-dst 667cbc44-a44f-4074-8978-b832249442c6 "" 45c85fa4-5014-408d-b82d-12121fb189d7 40c1ae3d-3ee8-412f-84df-dd7157fb700a

Mcast_Macs_Remote table
MAC _uuid ipaddr locator_set logical_switch
----------- ------------------------------------ ------ ------------------------------------ ------------------------------------
unknown-dst c7e3ab8f-219d-4e5d-84ed-36475bfa1705 "" 4df98102-7cc0-4286-a286-ecb597943f1d 40c1ae3d-3ee8-412f-84df-dd7157fb700a

Physical_Locator table
_uuid dst_ip encapsulation_type tunnel_key
------------------------------------ ----------- ------------------ ----------
d405d20d-c40f-4770-8b99-9f08f2610a9b "10.0.0.10" "vxlan_over_ipv4" []
c2e3fb86-440b-4dd0-8509-6eb77d448c53 "10.0.0.50" "vxlan_over_ipv4" []

Physical_Locator_Set table
_uuid locators
------------------------------------ --------------------------------------
45c85fa4-5014-408d-b82d-12121fb189d7 [c2e3fb86-440b-4dd0-8509-6eb77d448c53]
4df98102-7cc0-4286-a286-ecb597943f1d [d405d20d-c40f-4770-8b99-9f08f2610a9b]



---------------------------
When this issue occurred:
---------------------------

Bridge "ocata-l2gw1_vtep_ls1"
Port "2222-patch-vlan-l"
Interface "2222-patch-vlan-l"
type: patch
options: {peer="2222-patch-vlan-p"}

Port "vx1"
Interface "vx1"
type: vxlan
options:

{key="48", remote_ip="10.0.0.50"}

Port "vx2"
Interface "vx2"
type: vxlan
options:

{key="48", remote_ip="10.0.0.10"}

Port "ocata-l2gw1_vtep_ls1"
Interface "ocata-l2gw1_vtep_ls1"
type: internal

Mcast_Macs_Local table
MAC _uuid ipaddr locator_set logical_switch
----------- ------------------------------------ ------ ------------------------------------ ------------------------------------
unknown-dst b841e569-0c2e-4d77-b4a3-240416a5f481 "" 024e56e7-f56b-4fa0-9201-65ac6930e113 567bb87c-d5d9-4292-8eff-9dc04dccec1a

Mcast_Macs_Remote table
MAC _uuid ipaddr locator_set logical_switch
----------- ------------------------------------ ------ ------------------------------------ ------------------------------------
unknown-dst f4a9f429-5be3-49d9-8f35-d1b21a96ad10 "" 5603ff4c-4a46-4a70-adc9-32d2ee8b66b5 567bb87c-d5d9-4292-8eff-9dc04dccec1a
Physical_Locator table
_uuid dst_ip encapsulation_type tunnel_key
------------------------------------ ----------- ------------------ ----------
f8da2d44-e8d3-4a14-94b4-9549546aa4bf "10.0.0.10" "vxlan_over_ipv4" []
d804bff8-6922-4b28-93af-8ca650f203fb "10.0.0.50" "vxlan_over_ipv4" []

Physical_Locator_Set table
_uuid locators
------------------------------------ ----------------------------------------------------------------------------
024e56e7-f56b-4fa0-9201-65ac6930e113 [d804bff8-6922-4b28-93af-8ca650f203fb]
5603ff4c-4a46-4a70-adc9-32d2ee8b66b5 [d804bff8-6922-4b28-93af-8ca650f203fb, f8da2d44-e8d3-4a14-94b4-9549546aa4bf]