xfs: fix some minor sparse warnings

A couple of simple locking annotations and 0 vs NULL warnings.
Nothing that changes any code behaviour, just removes build noise.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_itable.c

@@ -541,8 +541,9 @@ xfs_bulkstat_single(
 	 * at the expense of the error case.
 	 */
 
-	ino = (xfs_ino_t)*lastinop;
-	error = xfs_bulkstat_one(mp, ino, buffer, sizeof(xfs_bstat_t), 0, &res);
+	ino = *lastinop;
+	error = xfs_bulkstat_one(mp, ino, buffer, sizeof(xfs_bstat_t),
+				 NULL, &res);
 	if (error) {
 		/*
 		 * Special case way failed, do it the "long" way