xfs: remove xfs_mod_incore_sb API

Now that there are no users of the bitfield based incore superblock
modification API, just remove the whole damn lot of it, including
all the bitfield definitions. This finally removes a lot of cruft
that has been around for a long time.

Credit goes to Christoph Hellwig for providing a great patch
connecting all the dots to enale us to do this. This patch is
derived from that work.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 1c11512..8c995a2 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -313,9 +313,8 @@
 extern int	xfs_mountfs(xfs_mount_t *mp);
 extern int	xfs_initialize_perag(xfs_mount_t *mp, xfs_agnumber_t agcount,
 				     xfs_agnumber_t *maxagi);
-
 extern void	xfs_unmountfs(xfs_mount_t *);
-extern int	xfs_mod_incore_sb(xfs_mount_t *, xfs_sb_field_t, int64_t, int);
+
 extern int	xfs_mod_icount(struct xfs_mount *mp, int64_t delta);
 extern int	xfs_mod_ifree(struct xfs_mount *mp, int64_t delta);
 extern int	xfs_mod_fdblocks(struct xfs_mount *mp, int64_t delta,