Get rid if ddir_trim() macro

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/io_u.c b/io_u.c
index 438ad5d..e8894d5 100644
--- a/io_u.c
+++ b/io_u.c
@@ -580,8 +580,8 @@
 	if (td_rw(td) && __should_check_rate(td, odir))
 		td->rate_pending_usleep[odir] -= usec;
 
-	if (ddir_trim(ddir))
-		return ddir;
+	if (ddir == DDIR_TRIM)
+		return DDIR_TRIM;
 
 	return ddir;
 }