xfs: use tr_growrtalloc for growing rt files

This is a regression from the following commit:

3d3c8b52 xfs: refactor xfs_trans_reserve() interface

Use the tr_growrtalloc log reservation for growing the
bitmap/summary files.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_rtalloc.c

@@ -842,7 +842,7 @@ xfs_growfs_rt_alloc(
 		/*
 		 * Reserve space & log for one extent added to the file.
 		 */
-		error = xfs_trans_reserve(tp, &M_RES(mp)->tr_growdata,
+		error = xfs_trans_reserve(tp, &M_RES(mp)->tr_growrtalloc,
 					  resblks, 0);
 		if (error)
 			goto error_cancel;