xfs: Add missing annotation to xfs_ail_check()

Sparse reports a warning at xfs_ail_check()

warning: context imbalance in xfs_ail_check() - unexpected unlock

The root cause is the missing annotation at xfs_ail_check()

Add the missing __must_hold(&ailp->ail_lock) annotation
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_trans_ail.c

@@ -32,6 +32,7 @@ STATIC void
 xfs_ail_check(
 	struct xfs_ail		*ailp,
 	struct xfs_log_item	*lip)
+	__must_hold(&ailp->ail_lock)
 {
 	struct xfs_log_item	*prev_lip;
 	struct xfs_log_item	*next_lip;