xfs: fix static and extern sparse warnings

The kbuild test robot indicated that there were some new sparse
warnings in fs/xfs/xfs_dquot_buf.c. Actually, there were a lot more
that is wasn't warning about, so fix them all up.

Reported-by: kbuild test robot
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_buf_item.c

@@ -809,7 +809,7 @@ xfs_buf_item_init(
  * Mark bytes first through last inclusive as dirty in the buf
  * item's bitmap.
  */
-void
+static void
 xfs_buf_item_log_segment(
 	struct xfs_buf_log_item	*bip,
 	uint			first,