LU-7734 lnet: introduce LNET_PEER_MULTI_RAIL flag bit

LU-7734 lnet: introduce LNET_PEER_MULTI_RAIL flag bit

Add lp_state as a flag word to lnet_peer, and add lp_lock
to protect it. This lock needs to be taken whenever the
field is updated, because setting or clearing a bit is
a read-modify-write cycle.

The lp_multi_rail is removed, its function is replaced by
the new LNET_PEER_MULTI_RAIL flag bit.

The helper lnet_peer_is_multi_rail() tests the bit.

Test-Parameters: trivial
Signed-off-by: Olaf Weber <olaf@sgi.com>
Change-Id: I7e5678d75b2563d26896d3e108ce8ece0487dc48