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/sun8i_emac.c b/drivers/net/sun8i_emac.c
index 0fa8ba9..3430b22 100644
--- a/drivers/net/sun8i_emac.c
+++ b/drivers/net/sun8i_emac.c
@@ -1005,6 +1005,6 @@
 	.probe  = sun8i_emac_eth_probe,
 	.ops    = &sun8i_emac_eth_ops,
 	.priv_auto	= sizeof(struct emac_eth_dev),
-	.platdata_auto	= sizeof(struct sun8i_eth_pdata),
+	.plat_auto	= sizeof(struct sun8i_eth_pdata),
 	.flags = DM_FLAG_ALLOC_PRIV_DMA,
 };