Merge tag 'u-boot-rockchip-20191118' of https://gitlab.denx.de/u-boot/custodians/u-boot-rockchip

- Add support for rockchip SoC: PX30, RK3308
- Add and migrate to use common dram driver: PX30, RK3328, RK3399
- Add rk3399 board Tinker-s support
- Board config update for Rock960, Rockpro64