dm: test: Add a test for of-platdata phandles

We have a test in dtoc for this feature, but not one in U-Boot itself.
Add a simple test that checks that the information comes through
correctly.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/clk/clk_sandbox.c b/drivers/clk/clk_sandbox.c
index 768fbb7..0ff1b49 100644
--- a/drivers/clk/clk_sandbox.c
+++ b/drivers/clk/clk_sandbox.c
@@ -124,8 +124,8 @@
 	{ }
 };
 
-U_BOOT_DRIVER(clk_sandbox) = {
-	.name		= "clk_sandbox",
+U_BOOT_DRIVER(sandbox_clk) = {
+	.name		= "sandbox_clk",
 	.id		= UCLASS_CLK,
 	.of_match	= sandbox_clk_ids,
 	.ops		= &sandbox_clk_ops,