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/tsec.c b/drivers/net/tsec.c
index 2288204..8c53059 100644
--- a/drivers/net/tsec.c
+++ b/drivers/net/tsec.c
@@ -905,7 +905,7 @@
 	.remove = tsec_remove,
 	.ops = &tsec_ops,
 	.priv_auto	= sizeof(struct tsec_private),
-	.platdata_auto	= sizeof(struct eth_pdata),
+	.plat_auto	= sizeof(struct eth_pdata),
 	.flags = DM_FLAG_ALLOC_PRIV_DMA,
 };
 #endif /* CONFIG_DM_ETH */