LU-7734 lnet: protect peer_ni credits

Currently multiple NIs can talk to the same peer_ni. The per-CPT
lnet_net_lock therefore no longer protects the lpni against
concurrent updates. To resolve this issue a spinlock is added
to the lnet_peer_ni, which must be locked when the peer NI
credits, delayed message queue, and delayed routed message queue
are modified. The lock is not taken when reporting credits.

Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Signed-off-by: Olaf Weber <olaf@sgi.com>
Change-Id: I52153680a74d43e595314b63487026cc3f6a5a8f
Reviewed-on: http://review.whamcloud.com/20702