[U-Boot] rockchip: mkimage: add support for rk3128 soc

[Philipp Tomsich]

> Add support for rk3128 package header in mkimage tool.
> 
> Signed-off-by: Kever Yang <kever.yang at rock-chips.com>
> ---
> 
>  tools/rkcommon.c | 1 +
>  1 file changed, 1 insertion(+)
> 

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