ARM: sunxi: Add support for using R_UART as console

The A23 only has UART0 muxed with MMC0. Some of the boards we
encountered expose R_UART as a set of pads.

Add support for R_UART so we can have a console while using mmc.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
diff --git a/arch/arm/include/asm/arch-sunxi/gpio.h b/arch/arm/include/asm/arch-sunxi/gpio.h
index de7a86a..7bb6499 100644
--- a/arch/arm/include/asm/arch-sunxi/gpio.h
+++ b/arch/arm/include/asm/arch-sunxi/gpio.h
@@ -172,6 +172,9 @@
 
 #define SUN4I_GPI4_SDC3		2
 
+#define SUN8I_GPL2_R_UART_TX	2
+#define SUN8I_GPL3_R_UART_RX	2
+
 /* GPIO pin pull-up/down config */
 #define SUNXI_GPIO_PULL_DISABLE	0
 #define SUNXI_GPIO_PULL_UP	1