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/rtc/pcf2127.c b/drivers/rtc/pcf2127.c
index 88ff8c5..57f8640 100644
--- a/drivers/rtc/pcf2127.c
+++ b/drivers/rtc/pcf2127.c
@@ -25,7 +25,7 @@
 
 static int pcf2127_rtc_read(struct udevice *dev, uint offset, u8 *buffer, uint len)
 {
-	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
+	struct dm_i2c_chip *chip = dev_get_parent_plat(dev);
 	struct i2c_msg msg;
 	int ret;