test: Mark all driver model tests with a flag

Add a flag for driver model tests, so we can do special processing for
them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/dm/test.h b/include/dm/test.h
index 6ac6672..dfbc82c 100644
--- a/include/dm/test.h
+++ b/include/dm/test.h
@@ -143,7 +143,8 @@
 };
 
 /* Declare a new driver model test */
-#define DM_TEST(_name, _flags)	UNIT_TEST(_name, _flags, dm_test)
+#define DM_TEST(_name, _flags) \
+	UNIT_TEST(_name, UT_TESTF_DM | (_flags), dm_test)
 
 /*
  * struct sandbox_sdl_plat - Platform data for the SDL video driver