xfs: remove unused tp arg from xfs_bmap_last_offset() and callers

remove unused transaction pointer from various
callchains leading to xfs_bmap_last_offset().

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
index aead369..a18000f 100644
--- a/fs/xfs/xfs_dir2_readdir.c
+++ b/fs/xfs/xfs_dir2_readdir.c
@@ -687,7 +687,7 @@
 	lock_mode = xfs_ilock_data_map_shared(dp);
 	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
 		rval = xfs_dir2_sf_getdents(dp, ctx);
-	else if ((rval = xfs_dir2_isblock(NULL, dp, &v)))
+	else if ((rval = xfs_dir2_isblock(dp, &v)))
 		;
 	else if (v)
 		rval = xfs_dir2_block_getdents(dp, ctx);