LU-10391 ptlrpc: change rq_self to struct lnet_nid

LU-10391 ptlrpc: change rq_self to struct lnet_nid

rq_self in struct ptlrpc_request can now store largs NIDs.
ptlrpc_connection_get() is also changed to received a
'struct lnet_nid'.

Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: If2ea7770e967e2f044f2b2300950b612463e130c
Reviewed-on: https://review.whamcloud.com/44636
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>