ramips: Add support for CJ-Hello HYC-G920

ramips: Add support for CJ-Hello HYC-G920

Hanyang Digitech Co., Ltd.
MSIP-CMM-HYD-HYC-G920
CJ-Hello HYC-G920

SoC		: MediaTek MT7621AT
RAM		: 256M (SK hynix H5TQ2G63FFR)
FLASH	: 16MB (Winbond W25Q128BV)
WiFi	: MediaTek MT7602EN bgn 2SS
WiFi	: MediaTek MT7612EN nac 2SS
BTN		: Reset
LED		: - Power RED
		  - WAN Green
		  - LAN {1-4}
		  - WiFi 2.4 GHz Blue
		  - WiFi 5 GHz Blue
		  - USB Green

**For MT7621 stage1 DDR Test**

UART	: J4 GND - 3V3 - TX - RX - GND / 57600-8N1

```
                MT7621   stage1 code 10:33:55 (ASIC)
                CPU=500000000 HZ BUS=166666666 HZ
```

**For u boot environment**

UART	: J4 GND - 3V3 - TX - RX - GND / 115200-8N1

**UART Menu**

```
	Please choose the operation:
		1: Load system code to SDRAM via TFTP.
		2: Load system code then write to Flash via TFTP.
		3: Boot system code via Flash (default).
		4: Entr boot command line interface.
		7: Load Boot Loader code then write to Flash via Serial.
		9: Load Boot Loader code then write to Flash via TFTP.
```

**Steps**

Press 4: Entr boot command line interface.

On the pormpt enter.
`setenv firmware_size 0xf60000`
Then enter.
`saveenv`
Then enter.
`reset`

**Device will reboot**

Set your IP 192.168.100.100/24
Connect your lan cable to wan port.

**On the UART Menu**

Press 2: Load system code then write to Flash via TFTP.

 Warning!! Erase Linux in Flash then burn new one. Are you sure?(Y/N) **enter** `Y`
 Please Input new ones /or Ctrl-C to discard
        Input device IP (192.168.100.55) ==:`192.168.100.55`
        Input server IP (192.168.100.100) ==:`192.168.100.100`
        Input Linux Kernel filename () ==:`openwrt-22.03.0-ramips-mt7621-hanyang_hyc-g920-squashfs-sysupgrade.bin`

After uploading firmware image, device will boot Openwrt.

Signed-off-by: Muhammad AL-Qadhy <m.ismael@gmail.com>