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/arch/riscv/include/asm/arch-fu540/gpio.h b/arch/riscv/include/asm/arch-fu540/gpio.h
index 0d16c59..b87282b 100644
--- a/arch/riscv/include/asm/arch-fu540/gpio.h
+++ b/arch/riscv/include/asm/arch-fu540/gpio.h
@@ -28,7 +28,7 @@
 };
 
 /* Details about a GPIO bank */
-struct sifive_gpio_platdata {
+struct sifive_gpio_plat {
 	void *base;     /* address of registers in physical memory */
 };