ipq40xx: add support for EZVIZ CS-W3-WD1200G EUP

ipq40xx: add support for EZVIZ CS-W3-WD1200G EUP

Hardware:
SOC:    Qualcomm IPQ4018
RAM:	128 MB Nanya NT5CC64M16GP-DI
FLASH:  16 MB Macronix MX25L12805D
ETH:    Qualcomm QCA8075 (4 Gigabit ports, 3xLAN, 1xWAN)
WLAN:   Qualcomm IPQ4018 (2.4 & 5 Ghz)
BUTTON: Shared WPS/Reset button
LED:    RGB Status/Power LED
SERIAL: Header J8 (UART, Left side of board). Numbered from
        top to bottom:
        (1) GND, (2) TX, (3) RX, (4) VCC (White triangle
        next to it).
        3.3v, 115200, 8N1

Tested/Working:
* Ethernet
* WiFi (2.4 and 5GHz)
* Status LED
* Reset Button (See note below)

Implementation notes:
* The shared WPS/Reset button is implemented as a Reset button
* I could not find a original firmware image to reverse engineer, meaning
currently it's not possible to flash OpenWrt through the Web GUI.

Installation (Through Serial console & TFTP):
1. Set your PC to fixed IP 192.168.1.12, Netmask 255.255.255.0, and connect to
one of the LAN ports
2. Rename the initramfs image to 'C0A8010B.img' and enable a TFTP server on
your pc, to serve the image
2. Connect to the router through serial (See connection properties above)
3. Hit a key during startup, to pause startup
4. type `setenv serverip 192.168.1.12`, to set the tftp server address
5. type `tftpboot`, to load the image from the laptop through tftp
6. type `bootm` to run the loaded image from memory
6. (If you want to return to stock firmware later, create an full MTD backup,
e.g. using instructions here https://openwrt.org/docs/guide-user/installation/generic.backup#create_full_mtd_backup)
7. Transfer the 'sysupgrade' OpenWrt firmware image from PC to router, e.g.:
`scp xxx-squashfs-sysupgrade.bin root@192.168.1.1:/tmp/upgrade.bin`
8. Run sysupgrade to permanently install OpenWrt to flash: `sysupgrade -n /tmp/upgrade.bin`

Revert to stock:
To revert to stock, you need the MTD backup from step 6 above:
1. Unpack the MTD backup archive
2. Transfer the 'firmware' partition image to the router (e.g. mtd8_firmware.backup)
3. On the router, do `mtd write mtd8_firmware.backup firmware`

Signed-off-by: Tom Brouwer <tombrouwer@outlook.com>
[removed BOARD_NAME, OpenWRT->OpenWrt, changed LED device name to board name]
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>