Include port capability in the port create message.

When a port created message is received in the Voltha Core, the Core will create a logical port if that port represents a UNI or NNI port. As part of the logical port creation the Core queries the adapter to retrieve its port capability. To prevent changes to the ports during that query the logical device is locked for that duration. Under load condition this latency can become significant enough that it has a ripple effect on all requests.

It is better for the adapters to provide the port capability at the same time when the port create message is sent. In fact, the adapters today send hardcoded port capability data to the Core. Therefore the port capability already exists at the time of port creation. In future, if adapters need to provide real-time port capabilities then the adapter can wait until it receives the port capability data before sending the port create message.

This Jira requires changes in the adapters, the Core as well as the protos. Originally, it was thought we could just add port capability to the port create message. However, this is not enough since we need a mechanism to store that data until a logical port is ready to be created. Thus, we will include the port capability as part of the Port proto definition.