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/usb/host/ehci-exynos.c b/drivers/usb/host/ehci-exynos.c
index 3728b23..d1ff3f4 100644
--- a/drivers/usb/host/ehci-exynos.c
+++ b/drivers/usb/host/ehci-exynos.c
@@ -259,6 +259,6 @@
 	.remove = ehci_usb_remove,
 	.ops	= &ehci_usb_ops,
 	.priv_auto	= sizeof(struct exynos_ehci),
-	.platdata_auto	= sizeof(struct exynos_ehci_platdata),
+	.plat_auto	= sizeof(struct exynos_ehci_platdata),
 	.flags	= DM_FLAG_ALLOC_PRIV_DMA,
 };