dm: Use access methods for dev/uclass private data

Most drivers use these access methods but a few do not. Update them.

In some cases the access is not permitted, so mark those with a FIXME tag
for the maintainer to check.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Pratyush Yadav <p.yadav@ti.com>
diff --git a/test/dm/test-fdt.c b/test/dm/test-fdt.c
index eb3c2cf..9e8c290 100644
--- a/test/dm/test-fdt.c
+++ b/test/dm/test-fdt.c
@@ -25,7 +25,7 @@
 
 static int testfdt_drv_ping(struct udevice *dev, int pingval, int *pingret)
 {
-	const struct dm_test_pdata *pdata = dev->plat;
+	const struct dm_test_pdata *pdata = dev_get_plat(dev);
 	struct dm_test_priv *priv = dev_get_priv(dev);
 
 	*pingret = pingval + pdata->ping_add;
@@ -288,7 +288,7 @@
 		ret = uclass_find_device(UCLASS_TEST_FDT, i, &dev);
 		ut_assert(!ret);
 		ut_assert(!dev_get_priv(dev));
-		ut_assert(dev->plat);
+		ut_assert(dev_get_plat(dev));
 	}
 
 	ut_assertok(dm_check_devices(uts, num_devices));