test: Drop struct dm_test_state

Driver model is a core part of U-Boot. We don't really need to have a
separate test structure for the driver model tests and it makes it harder
to write a test if you have to think about which type of test it is.

Subsume the fields from struct dm_test_state into struct unit_test_state
and delete the former.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/test-driver.c b/test/dm/test-driver.c
index ca7626a..63dc9d3 100644
--- a/test/dm/test-driver.c
+++ b/test/dm/test-driver.c
@@ -116,10 +116,8 @@
 
 static int test_manual_probe(struct udevice *dev)
 {
-	struct dm_test_state *dms = uts->priv;
-
 	dm_testdrv_op_count[DM_TEST_OP_PROBE]++;
-	if (!dms->force_fail_alloc)
+	if (!uts->force_fail_alloc)
 		dev_set_priv(dev, calloc(1, sizeof(struct dm_test_priv)));
 	if (!dev_get_priv(dev))
 		return -ENOMEM;