[U-Boot] rockchip: set SYS_NS16550_MEM32 for all SoCs

[Philipp Tomsich]

> 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
> c3c0331db1fb7b1f4ff41e144fc04353b37c785c.
> 
> Signed-off-by: Kever Yang <kever.yang at rock-chips.com>
> Signed-off-by: Jonathan Gray <jsg at jsg.id.au>
> Cc: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>
> ---
>  include/configs/rockchip-common.h | 2 ++
>  1 file changed, 2 insertions(+)
> 

Reviewed-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>