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/net/ftmac100.c b/drivers/net/ftmac100.c
index 20b8e35..de7ec4d 100644
--- a/drivers/net/ftmac100.c
+++ b/drivers/net/ftmac100.c
@@ -441,7 +441,7 @@
 	.probe	= ftmac100_probe,
 	.ops	= &ftmac100_ops,
 	.priv_auto	= sizeof(struct ftmac100_data),
-	.platdata_auto	= sizeof(struct eth_pdata),
+	.plat_auto	= sizeof(struct eth_pdata),
 	.flags	= DM_FLAG_ALLOC_PRIV_DMA,
 };
 #endif