dm: Add a test for of-platdata parent information

Add a simple test that we can obtain the correct parent for an I2C
device. This requires updating the driver names to match the compatible
strings, adding them to the devicetree and enabling a few options.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/i2c/sandbox_i2c.c b/drivers/i2c/sandbox_i2c.c
index 57b1c60..2cbdaf9 100644
--- a/drivers/i2c/sandbox_i2c.c
+++ b/drivers/i2c/sandbox_i2c.c
@@ -93,8 +93,8 @@
 	{ }
 };
 
-U_BOOT_DRIVER(i2c_sandbox) = {
-	.name	= "i2c_sandbox",
+U_BOOT_DRIVER(sandbox_i2c) = {
+	.name	= "sandbox_i2c",
 	.id	= UCLASS_I2C,
 	.of_match = sandbox_i2c_ids,
 	.ops	= &sandbox_i2c_ops,