dm: rpi: Convert GPIO driver to driver model

Convert the BCM2835 GPIO driver to use driver model, and switch over
Raspberry Pi to use this, since it is the only board.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>

arch/arm/include/asm/arch-bcm2835/gpio.h

@@ -52,4 +52,13 @@ struct bcm2835_gpio_regs {
 	u32 gppudclk[2];
 };
 
+/**
+ * struct bcm2835_gpio_platdata - GPIO platform description
+ *
+ * @base: Base address of GPIO controller
+ */
+struct bcm2835_gpio_platdata {
+	unsigned long base;
+};
+
 #endif /* _BCM2835_GPIO_H_ */