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/reset.c b/test/dm/reset.c
index 8232807..f5f3661 100644
--- a/test/dm/reset.c
+++ b/test/dm/reset.c
@@ -39,7 +39,7 @@
 	return 0;
 }
 
-DM_TEST(dm_test_reset_base, DM_TESTF_SCAN_FDT);
+DM_TEST(dm_test_reset_base, UT_TESTF_SCAN_FDT);
 
 static int dm_test_reset(struct unit_test_state *uts)
 {
@@ -64,7 +64,7 @@
 
 	return 0;
 }
-DM_TEST(dm_test_reset, DM_TESTF_SCAN_FDT);
+DM_TEST(dm_test_reset, UT_TESTF_SCAN_FDT);
 
 static int dm_test_reset_bulk(struct unit_test_state *uts)
 {
@@ -94,4 +94,4 @@
 
 	return 0;
 }
-DM_TEST(dm_test_reset_bulk, DM_TESTF_SCAN_FDT);
+DM_TEST(dm_test_reset_bulk, UT_TESTF_SCAN_FDT);