test: Handle driver model reinit in test_pre_run()

For driver model tests we want to reinit the data structures so that
everything is in a known state before the test runs. This avoids one test
changing something that breaks a subsequent tests.

Move the call for this into test_pre_run().

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/test-dm.c b/test/dm/test-dm.c
index 569ffbb..ceeac3f 100644
--- a/test/dm/test-dm.c
+++ b/test/dm/test-dm.c
@@ -24,10 +24,10 @@
 struct unit_test_state global_dm_test_state;
 static struct dm_test_state _global_priv_dm_test_state;
 
-/* Get ready for testing */
-static int dm_test_init(struct unit_test_state *uts, bool of_live)
+int dm_test_init(struct unit_test_state *uts)
 {
 	struct dm_test_state *dms = uts->priv;
+	bool of_live = uts->of_live;
 
 	memset(dms, '\0', sizeof(*dms));
 	gd->dm_root = NULL;
@@ -70,7 +70,7 @@
 
 	printf("Test: %s: %s%s\n", test->name, fname,
 	       !of_live ? " (flat tree)" : "");
-	ut_assertok(dm_test_init(uts, of_live));
+	uts->of_live = of_live;
 
 	ut_assertok(test_pre_run(uts, test));
 
diff --git a/test/test-main.c b/test/test-main.c
index 6f0d32f..f14b7b0 100644
--- a/test/test-main.c
+++ b/test/test-main.c
@@ -30,6 +30,9 @@
 
 int test_pre_run(struct unit_test_state *uts, struct unit_test *test)
 {
+	if (test->flags & UT_TESTF_DM)
+		ut_assertok(dm_test_init(uts));
+
 	ut_set_skip_delays(uts, false);
 
 	uts->start = mallinfo();