ssa.c: Change ssa_add_access_consumer to take pointer to gid structure

rather than gid structure itself (on the stack)

Signed-off-by: Hal Rosenstock <hal@mellanox.com>
[ssa.c ssa_ctrl.h]: Change ssa_db_update struct to contain gid rather than *gid

as this is safer since *gid in some cases was referring to
some memory on stack in thread which might be changing by
the time other thread gets/handles the update message

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