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>

include/dm/platform_data/serial_pl01x.h

@@ -20,7 +20,7 @@ enum pl01x_type {
  * @skip_init: Don't attempt to change port configuration (also means @clock
  * is ignored)
  */
-struct pl01x_serial_platdata {
+struct pl01x_serial_plat {
 	unsigned long base;
 	enum pl01x_type type;
 	unsigned int clock;