uar_lock spinlock was used in mlx4_ib_cq_arm without being initialized
(this only affects 32-bit archs, because uar_lock is not used on
64-bit archs and MLX4_INIT_DOORBELL_LOCK() is a NOP).
Signed-off-by: NJack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>