rockchip: add FriendlyElec NanoPi R6C

rockchip: add FriendlyElec NanoPi R6C

Hardware Spec
 -SoC: Rockchip RK3588S
       CPU: Quad-core ARM Cortex-A76(up to 2.4GHz) and quad-core Cortex-A55 CPU (up to 1.8GHz)
       GPU: Mali-G610 MP4, compatible with OpenGLES 1.1, 2.0, and 3.2, OpenCL up to 2.2 and Vulkan1.2
       VPU: 8K@60fps H.265 and VP9 decoder, 8K@30fps H.264 decoder, 4K@60fps AV1 decoder, 8K@30fps H.264 and H.265
       NPU: 6TOPs, supports INT4/INT8/INT16/FP16
 -RAM: 64-bit 4GB/8GB LPDDR4X at 2133MHz
 -Flash: 32GB/None eMMC, at HS400 mode
 -Ethernet: one Native Gigabit Ethernet, and one PCIe 2.5G Ethernet
 -USB: one USB 3.0 Type-A and one USB 2.0 Type-A
 -PCIe: one M.2 Key M connector with PCIe 2.1 x1
 -HDMI:
       compatible with HDMI2.1, HDMI2.0, and HDMI1.4 operation
       support up to 7680x4320@60Hz
       Support RGB/YUV(up to 10bit) format
 -microSD: support up to SDR104 mode
 -GPIO:
       30-pin 2.54mm header connector
       up to 1x SPI, 3x UARTs, 3x I2Cs, 2x SPDIFs, 1x I2Ss, 3x PWMs, 20x GPIOs
 -Debug: UART via 3-Pin 2.54mm header, or on-board USB-C to UART
 -LEDs: 4 x GPIO Controlled LED (SYS, WAN, LAN, LED1)
 -others:
        2 Pin 1.27/1.25mm RTC battery input connector for low power RTC IC HYM8563TS
        MASK button for eMMC update
        one user button
 -Power supply: USB-C, support PD, 5V/9V/12V/20V input
 -PCB: 8 Layer, 62x90x1.6mm
 -Ambient Operating Temperature: 0℃ to 70℃

Installation:

Uncompress the OpenWrt sysupgrade and write image to the SD card using dd (dd if=*.img of=/*)

eMMC Installation:

Boot from the SD card
Uncompress the OpenWrt sysupgrade image
fash to eMMC : dd if=*.img of=/dev/mmcblk1
sync
remove SD card
reboot

Signed-off-by: Antonio Flores <antflores627@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/16275
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>