staging: lustre: 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

Signed-off-by: frank zago <fzago@cray.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5396
Reviewed-on: http://review.whamcloud.com/11295


Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Patrick Farrell <paf@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>