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/mscc_eswitch/servalt_switch.c b/drivers/net/mscc_eswitch/servalt_switch.c
index 8855640..59c0d85 100644
--- a/drivers/net/mscc_eswitch/servalt_switch.c
+++ b/drivers/net/mscc_eswitch/servalt_switch.c
@@ -524,5 +524,5 @@
 	.remove				= servalt_remove,
 	.ops				= &servalt_ops,
 	.priv_auto		= sizeof(struct servalt_private),
-	.platdata_auto	= sizeof(struct eth_pdata),
+	.plat_auto	= sizeof(struct eth_pdata),
 };