xfs: add more statics & drop some unused functions

A lot more functions could be made static, but they need
forward declarations; this does some easy ones, and also
found a few unused functions in the process.

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Felix Blyakher <felixb@sgi.com>
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 5c6f092..8b6c9e8 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1568,7 +1568,7 @@
  *
  * The m_sb_lock must be held when this routine is called.
  */
-int
+STATIC int
 xfs_mod_incore_sb_unlocked(
 	xfs_mount_t	*mp,
 	xfs_sb_field_t	field,