rockchip: px30: Add support for UART3 as serial output

Add the UART3 base definition for serial output, which is used on some
PX30 SoM boards.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Change-Id: I8490b15c9f129a33c01cb78bd78675014bc7b015

plat/rockchip/px30/px30_def.h

@@ -54,6 +54,9 @@
 #define UART2_BASE		0xff160000
 #define UART2_SIZE		SIZE_K(64)
 
+#define UART3_BASE		0xff168000
+#define UART3_SIZE		SIZE_K(64)
+
 #define UART5_BASE		0xff178000
 #define UART5_SIZE		SIZE_K(64)