ramips: add support for OrayBox X1

ramips: add support for OrayBox X1

Add support for OrayBox X1. It is a 802.11n router, based on MediaTek MT7628N.

Specifications:
SoC: MediaTek MT7628N (580MHz)
RAM: 64 MiB
Flash: 16 MiB NOR (Winbond W25Q128JVSIQ)
Wireless: 802.11b/g/n 2x2 2.4GHz (Built In)
Ethernet: 1x 100Mbps only
USB: 1x USB Type-A 2.0 Host Port
Button: 1x "Reset" button
LED: 1x Blue LED + 1x Red LED + 1x White LED
Power: 5V Micro-USB input

Manufacturer Page:
https://pgy.oray.com/router/x1.html/parameter

Flash Layout:
0x000000000000-0x000000030000 : "u-boot"
0x000000030000-0x000000040000 : "kpanic"
0x000000040000-0x000000050000 : "factory"
0x000000050000-0x000000fe0000 : "firmware"
0x000000fe0000-0x000000ff0000 : "bdinfo"
0x000000ff0000-0x000001000000 : "reserve"

Install via SSH:
Original firmware is based on OpenWRT, but SSH is not start by default,
You should enable it first

1. Login into web admin (10.168.1.1), default password is 'admin'
2. Open the following link, and the result should be {"code":0};
SSH is now started, username is root, password is same as web admin password
http://10.168.1.1/cgi-bin/oraybox?_api=ssh_set&enabled=1
4. You can flash firmware via mtd: mtd write /tmp/firmware_image.bin firmware

Signed-off-by: Bin We <me@udp.pw>