Layer Protocol Name attribute of MEG object need to be mandatory

[kgkishore]

Observation: Layer Protocol Name & Layer protocol qualifier attribute of (MEP & MIP) MEG object to be updated in yang as mandatory attribute

   +--ro meg* [uuid]
   |  +--ro mep* [local-id]
   |  |  +--ro layer-protocol-name?        tapi-common:layer-protocol-name
   |  |  +--ro layer-protocol-qualifier?   tapi-common:layer-protocol-qualifier

   |  |  +--ro local-id                    string

   |  |  +--ro name* [value-name]

   |  |  |  +--ro value-name    string

   |  |  |  +--ro value?        string

   |  |  +--ro operational-state?          operational-state

   |  |  +--ro lifecycle-state?            lifecycle-state
   |  +--ro mip* [local-id]
   |  |  +--ro layer-protocol-name?        tapi-common:layer-protocol-name
   |  |  +--ro layer-protocol-qualifier?   tapi-common:layer-protocol-qualifier