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/mmc/sandbox_mmc.c b/drivers/mmc/sandbox_mmc.c
index ece0e2d..17c6cea 100644
--- a/drivers/mmc/sandbox_mmc.c
+++ b/drivers/mmc/sandbox_mmc.c
@@ -148,5 +148,5 @@
 	.bind		= sandbox_mmc_bind,
 	.unbind		= sandbox_mmc_unbind,
 	.probe		= sandbox_mmc_probe,
-	.platdata_auto	= sizeof(struct sandbox_mmc_plat),
+	.plat_auto	= sizeof(struct sandbox_mmc_plat),
 };