dm: treewide: Rename 'platdata' variables to just 'plat'

We use 'priv' for private data but often use 'platdata' for platform data.
We can't really use 'pdata' since that is ambiguous (it could mean private
or platform data).

Rename some of the latter variables to end with 'plat' for consistency.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/gpio/pca953x_gpio.c b/drivers/gpio/pca953x_gpio.c
index 32d4a83..239c0f7 100644
--- a/drivers/gpio/pca953x_gpio.c
+++ b/drivers/gpio/pca953x_gpio.c
@@ -385,6 +385,6 @@
 	.id		= UCLASS_GPIO,
 	.ops		= &pca953x_ops,
 	.probe		= pca953x_probe,
-	.platdata_auto	= sizeof(struct pca953x_info),
+	.plat_auto	= sizeof(struct pca953x_info),
 	.of_match	= pca953x_ids,
 };