IB/mthca: Fix lid used for sending traps

The SM LID used to send traps to is incorrectly set to port LID.  This
is a regression from 2.6.17 -- after a PortInfo MAD is received, no
traps are sent to the SM LID.  The traps go to the loopback interface
instead, and are dropped there.  The SM LID should be taken from the
sm_lid of the PortInfo response.

The bug was introduced by commit 12bbb2b7:
	IB/mthca: Add client reregister event generation

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Michael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>