RDMA/core: Annotate CMA unlock helper routine

Fix the following sparse error by adding annotation to
cm_queue_work_unlock() that it releases cm_id_priv->lock lock.

 drivers/infiniband/core/cm.c:936:24: warning: context imbalance in
 'cm_queue_work_unlock' - unexpected unlock

Fixes: e83f195a

 ("RDMA/cm: Pull duplicated code into cm_queue_work_unlock()")
Link: https://lore.kernel.org/r/20200611130045.1994026-1-leon@kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>