sandbox: Disable I2C emulators in SPL

These cannot work with of-platdata since they currently need the
devicetree at runtime. Disable the emulators and the sandbox I2C driver
that needs them. We can enable these later, if needed for testing.

Switch the of_plat_parent test over to use a simple bus instead.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
diff --git a/test/dm/of_platdata.c b/test/dm/of_platdata.c
index cfc43a5..26c5092 100644
--- a/test/dm/of_platdata.c
+++ b/test/dm/of_platdata.c
@@ -210,11 +210,11 @@
 /* Test that device parents are correctly set up */
 static int dm_test_of_plat_parent(struct unit_test_state *uts)
 {
-	struct udevice *rtc, *i2c;
+	struct udevice *dev, *bus;
 
-	ut_assertok(uclass_first_device_err(UCLASS_RTC, &rtc));
-	ut_assertok(uclass_first_device_err(UCLASS_I2C, &i2c));
-	ut_asserteq_ptr(i2c, dev_get_parent(rtc));
+	ut_assertok(uclass_first_device_err(UCLASS_SIMPLE_BUS, &bus));
+	ut_assertok(device_first_child_err(bus, &dev));
+	ut_asserteq_ptr(bus, dev_get_parent(dev));
 
 	return 0;
 }