test: Rename unit-test flags

The UT_TESTF_ macros read as 'unit test test flags' which is not right.
Rename to UTF ('unit test flags').

This has the benefit of being shorter, which helps keep UNIT_TEST()
declarations on a single line.

Give the enum a name and reference it from the UNIT_TEST() macros while
we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/clk.c b/test/dm/clk.c
index a966471..922b053 100644
--- a/test/dm/clk.c
+++ b/test/dm/clk.c
@@ -47,7 +47,7 @@
 	return 0;
 }
 
-DM_TEST(dm_test_clk_base, UT_TESTF_SCAN_FDT);
+DM_TEST(dm_test_clk_base, UTF_SCAN_FDT);
 
 static int dm_test_clk(struct unit_test_state *uts)
 {
@@ -187,7 +187,7 @@
 	ut_assertok(device_remove(dev_test, DM_REMOVE_NORMAL));
 	return 0;
 }
-DM_TEST(dm_test_clk, UT_TESTF_SCAN_FDT);
+DM_TEST(dm_test_clk, UTF_SCAN_FDT);
 
 static int dm_test_clk_bulk(struct unit_test_state *uts)
 {
@@ -225,4 +225,4 @@
 
 	return 0;
 }
-DM_TEST(dm_test_clk_bulk, UT_TESTF_SCAN_FDT);
+DM_TEST(dm_test_clk_bulk, UTF_SCAN_FDT);