ssa.c: Generate IBV_EVENT_SM_CHANGE event

This is a workaround for Mellanox drivers. Those drivers don't generate
IBV_EVENT_SM_CHANGE event. But IBV_EVENT_CLIENT_REREGISTER event
is generated in case of SM change. ssa_ctrl_device could check
if the SM lid was changed and forward to upstream and downstream
IBV_EVENT_SM_CHANGE event instead of the original event.

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>