rockchip: add HINLINK H66K / H68K support

rockchip: add HINLINK H66K / H68K support

Hardware (common):
- RK3568 SoC
- 2/4GB LPDDR4
- 1x HDMI Type A
- 3.5mm jack with mic
- 1x PCIE 2.0 WiFi slot
- 1x USB 3.0, 2x USB 2.0
- 2x 2.5GbE RTL8125B Ethernet
- MicroSD card slot / eMMC 32GB

Additions to HINLINK H68K:
- 2x 1GbE RTL8211F/YT8531 Ethernet

Installation:
  Use dd or balenaEtcher to flash the firmware.

Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>
Link: https://github.com/openwrt/openwrt/pull/21270
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>