dm: Rename DM test flags to make them more generic

The test flags used by driver model are currently not available to other
tests. Rather than creating two sets of flags, make these flags generic
by changing the DM_ prefix to UT_ and moving them to the test.h header.

This will allow adding other test flags without confusion.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/sound.c b/test/dm/sound.c
index 9cb9961..b73f6ab 100644
--- a/test/dm/sound.c
+++ b/test/dm/sound.c
@@ -33,7 +33,7 @@
 
 	return 0;
 }
-DM_TEST(dm_test_sound, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+DM_TEST(dm_test_sound, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
 
 /* Test of the 'start beep' operations */
 static int dm_test_sound_beep(struct unit_test_state *uts)
@@ -54,4 +54,4 @@
 
 	return 0;
 }
-DM_TEST(dm_test_sound_beep, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+DM_TEST(dm_test_sound_beep, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);