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_iomap.c b/fs/xfs/xfs_iomap.c
index 3b80eba..6c5eb4c 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -730,7 +730,7 @@
 			 */
 			nimaps = 1;
 			end_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
-			error = xfs_bmap_last_offset(NULL, ip, &last_block,
+			error = xfs_bmap_last_offset(ip, &last_block,
 							XFS_DATA_FORK);
 			if (error)
 				goto trans_cancel;