dm: treewide: Rename ..._platdata variables to just ..._plat

Try to maintain some consistency between these variables by using _plat as
a suffix for them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/video/bcm2835.c b/drivers/video/bcm2835.c
index 95662f1..9326999 100644
--- a/drivers/video/bcm2835.c
+++ b/drivers/video/bcm2835.c
@@ -13,7 +13,7 @@
 
 static int bcm2835_video_probe(struct udevice *dev)
 {
-	struct video_uc_platdata *plat = dev_get_uclass_plat(dev);
+	struct video_uc_plat *plat = dev_get_uclass_plat(dev);
 	struct video_priv *uc_priv = dev_get_uclass_priv(dev);
 	int ret;
 	int w, h, pitch;