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/gpio/sifive-gpio.c b/drivers/gpio/sifive-gpio.c
index 19239f5..4be8d4f 100644
--- a/drivers/gpio/sifive-gpio.c
+++ b/drivers/gpio/sifive-gpio.c
@@ -172,7 +172,7 @@
 	.id	= UCLASS_GPIO,
 	.of_match = sifive_gpio_match,
 	.ofdata_to_platdata = of_match_ptr(sifive_gpio_ofdata_to_platdata),
-	.platdata_auto	= sizeof(struct sifive_gpio_platdata),
+	.plat_auto	= sizeof(struct sifive_gpio_platdata),
 	.ops	= &sifive_gpio_ops,
 	.probe	= sifive_gpio_probe,
 };