LU-14668 lnet: Lock primary NID logic

LU-14668 lnet: Lock primary NID logic

If a peer is created by Lustre make sure to lock that peer's
primary NID. This peer can be discovered in the background.
There is no need to block until discovery is complete, as Lustre
can continue on with the primary NID it provided.

Discovery will populate the peer with other interfaces the peer has
but will not change the peer's primary NID. It can also delete
peer's NIDs which Lustre told it about (not the Primary NID).

If a peer has been manually discovered via
   lnetctl discover <nid>
command, then make sure to delete the manually discovered
peer and recreate it with the Lustre NID information
provided for us.

Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: I8fc8a69caccca047e3085bb33d026a3f09fb359b