[U-Boot] rockchip: rk3036: enable rockusb support on rk3036 based device

[Philipp Tomsich]

> Rockchip Rockusb driver already merged. So we enable rockusb
> support on rk3036 based device.
> 
> Signed-off-by: Eddie Cai <eddie.cai.linux at gmail.com>
> ---
>  arch/arm/mach-rockchip/Kconfig | 2 ++
>  1 file changed, 2 insertions(+)
> 

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