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/iommu.c b/test/dm/iommu.c
index acea5f2..c5dd917 100644
--- a/test/dm/iommu.c
+++ b/test/dm/iommu.c
@@ -38,7 +38,7 @@
 
 	return 0;
 }
-DM_TEST(dm_test_iommu, UT_TESTF_SCAN_FDT);
+DM_TEST(dm_test_iommu, UTF_SCAN_FDT);
 
 static int dm_test_iommu_noiommu(struct unit_test_state *uts)
 {
@@ -66,7 +66,7 @@
 
 	return 0;
 }
-DM_TEST(dm_test_iommu_noiommu, UT_TESTF_SCAN_FDT);
+DM_TEST(dm_test_iommu_noiommu, UTF_SCAN_FDT);
 
 static int dm_test_iommu_pci(struct unit_test_state *uts)
 {
@@ -81,7 +81,7 @@
 
 	return 0;
 }
-DM_TEST(dm_test_iommu_pci, UT_TESTF_SCAN_FDT);
+DM_TEST(dm_test_iommu_pci, UTF_SCAN_FDT);
 
 static int dm_test_iommu_pci_noiommu(struct unit_test_state *uts)
 {
@@ -96,4 +96,4 @@
 
 	return 0;
 }
-DM_TEST(dm_test_iommu_pci_noiommu, UT_TESTF_SCAN_FDT);
+DM_TEST(dm_test_iommu_pci_noiommu, UTF_SCAN_FDT);