ramips: add support for JCG Q20
JCG Q20 is an AX 1800M router.
Hardware specs:
SoC: MediaTek MT7621AT
Flash: Winbond W29N01HV 128 MiB
RAM: Winbond W632GU6NB-11 256 MiB
WiFi: MT7915 2.4/5 GHz 2T2R
Ethernet: 10/100/1000 Mbps x3
LED: Status (red / blue)
Button: Reset, WPS
Power: DC 12V,1A
Flash instructions:
Upload factory.bin in stock firmware's upgrade page,
do not preserve settings.
MAC addresses map:
0x00004 *:3e wlan2g/wlan5g
0x3fff4 *:3c lan/label
0x3fffa *:3c wan
Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>