staging: lustre: lustre/ldlm: Fixed sparse warnings

Added __acquires / __releases sparse locking annotations
to lock_res_and_lock() and unlock_res_and_lock() functions
in l_lock.c, to fix below sparse warnings:

l_lock.c:47:22: warning: context imbalance in 'lock_res_and_lock' - wrong count at exit
l_lock.c:61:6: warning: context imbalance in 'unlock_res_and_lock' - unexpected unlock

Signed-off-by: Nayeemahmed Badebade <itachi.opsrc@gmail.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>