dm: treewide: Rename ..._platdata variables to just ..._plat

Try to maintain some consistency between these variables by using _plat as
a suffix for them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 96d1de6..2b445f2 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -59,7 +59,7 @@
 	.remove = xhci_deregister,
 	.of_match = xhci_pci_ids,
 	.ops	= &xhci_usb_ops,
-	.plat_auto	= sizeof(struct usb_platdata),
+	.plat_auto	= sizeof(struct usb_plat),
 	.priv_auto	= sizeof(struct xhci_ctrl),
 	.flags	= DM_FLAG_ALLOC_PRIV_DMA,
 };