rockchip: set SYS_NS16550_MEM32 for all SoCs

Add back part of patch send out as
'rockchip: enable SYS_NS16550 for all SoCs by default' that seems to have
gotten lost when it got merged to set SYS_NS16550_MEM32.

Allows serial output to work on tinker-rk3288 again after
c3c0331db1.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Jonathan Gray <jsg@jsg.id.au>
Cc: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

include/configs/rockchip-common.h

@@ -7,6 +7,8 @@
 #define _ROCKCHIP_COMMON_H_
 #include <linux/sizes.h>
 
+#define CONFIG_SYS_NS16550_MEM32
+
 #ifndef CONFIG_SPL_BUILD
 
 /* First try to boot from SD (index 0), then eMMC (index 1) */