LU-5396: add sparse locking annotations

LU-5396: add sparse locking annotations

Adds __acquires / __releases / __must_hold sparse locking annotations to
several functions.

Fixes sparse warnings such as:

libcfs/libcfs/hash.c:127:1: warning: context imbalance in 'cfs_hash_spin_lock'
    - wrong count at exit
libcfs/libcfs/hash.c:133:1: warning: context imbalance in 'cfs_hash_spin_unlock'
    - unexpected unlock
libcfs/libcfs/hash.c:141:9: warning: context imbalance in 'cfs_hash_rw_lock'
    - wrong count at exit
include/linux/rwlock_api_smp.h:221:9: warning: context imbalance in
    'cfs_hash_rw_unlock' - unexpected unlock

Change-Id: I91834ea62a2bc21ee853a80b0b266e3d0e960bc3
Signed-off-by: frank zago <fzago@cray.com>
Reviewed-on: http://review.whamcloud.com/11295
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Jenkins
Reviewed-by: Patrick Farrell <paf@cray.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>