Merge tag 'u-boot-rockchip-20201031' of https://gitlab.denx.de/u-boot/custodians/u-boot-rockchip

- New PX30 board: Engicam PX30.Core;
- Fix USB HID support for rock960;
- Remove host endianness dependency for rockchip mkimage;
- dts update for rk3288-tinker;
- Enable console MUX for some ROCKPi boards;
- Add config-based ddr selection for px30;