2.2.1 port-capabilities support in port-mapping

According to the device model, there are two ways to get the port-capabilities of the device in 2.2.1 models: 

1. Through the supported-interface-capability leaf-list under ports:                                                                                      +--rw circuit-packs* [circuit-pack-name]

           | +--rw ports* [port-name]

           |       +--ro supported-interface-capability* identityref

2. Port-capabilities under, ports sub-tree.

           +--rw circuit-packs* [circuit-pack-name]

               | +--rw ports* [port-name]

                  | +--ro org-openroadm-port-capability:port-capabilities
                     | +--ro org-openroadm-port-capability:supported-interface-capability* [if-cap-type]

Currently port-mapping only supports the #1. 

Add the code to enable to get the supported-interface-capability from port-capabilities as well.