rockchip: rk3328: enable USB mass storage on Renegade

This is very useful to access the LibreComputer eMMC as removable
storage from a PC (e.g. like so `ums 0 mmc 0`). It has been tested as
working on my Renegade board.

Signed-off-by: Leonidas P. Papadakos <papadakospan at gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>