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/demo/demo-shape.c b/drivers/demo/demo-shape.c
index 0f5cda2..cc99f3e 100644
--- a/drivers/demo/demo-shape.c
+++ b/drivers/demo/demo-shape.c
@@ -194,5 +194,5 @@
 	.probe = dm_shape_probe,
 	.remove = dm_shape_remove,
 	.priv_auto	= sizeof(struct shape_data),
-	.platdata_auto	= sizeof(struct dm_demo_pdata),
+	.plat_auto	= sizeof(struct dm_demo_pdata),
 };