[XFS] Second part buftarg cleanup, don't poke inside a buftarg here anymore

SGI Modid: 2.5.x-xfs:slinx:149232a

fs/xfs/xfs_log_recover.c

@@ -972,7 +972,7 @@ xlog_find_tail(xlog_t		*log,
 	 * We can't recover this device anyway, so it won't matter.
 	 */
 
-	if (!bdev_read_only(log->l_mp->m_logdev_targp->pbr_bdev)) {
+	if (!xfs_readonly_buftarg(log->l_mp->m_logdev_targp)) {
 		error = xlog_clear_stale_blocks(log, tail_lsn);
 	}
 #endif