rockchip: px30: add uart5 as option for serial output

The px30 mini-evb can use either uart2 (muxed with the sd-card pins) or
uart5 via its pin header for serial output. Uart5 is especially useful
when needing to boot from the sd-card, where uart2 obviously is not
useable.

So add the uart5 constants and it as uart option for the serial-param
handler.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Change-Id: Ib88df7a55d761ee104d312c9953a13de3beba1c4
diff --git a/plat/rockchip/px30/px30_def.h b/plat/rockchip/px30/px30_def.h
index 021165a..9b8ccfc 100644
--- a/plat/rockchip/px30/px30_def.h
+++ b/plat/rockchip/px30/px30_def.h
@@ -54,6 +54,9 @@
 #define UART2_BASE		0xff160000
 #define UART2_SIZE		SIZE_K(64)
 
+#define UART5_BASE		0xff178000
+#define UART5_SIZE		SIZE_K(64)
+
 #define I2C0_BASE		0xff180000
 #define I2C0_SIZE		SIZE_K(64)