ipq807x: add support for TP-Link EAP660 HD v1

ipq807x: add support for TP-Link EAP660 HD v1

Specifications:
* SoC: Qualcomm IPQ8072A (64-bit Quad-core Arm Cortex-A53 @ 2200MHz)
* Memory: 2x ESMT M15T4G16256A-DEBG2G (1 GiB DDR3-1866 13-13-13)
* Serial Port: 3v3 TTL 115200n8
* Wi-Fi: QCN5054 (4x4 5 GHz 802.11ax)
* Wi-Fi: QCN5024 (4x4 2.4 GHz 802.11b/g/n/ax)
* Ethernet: QCA8081 (10/100/1000/2.5GBASE-T)
* Flash: Winbond W29N01HZSINF (128 MiB)
* LEDs: 1x Blue Status (GPIO 42 Active High)
* Buttons: 1x Reset (GPIO 50 Active Low)

Installation Instructions (Serial+TFTP):
1. Solder 4 pin header to JP1 and bridge pads of R58 and R62.
2. Connect 3V3 TTL port to TX, RX, and GND, which are positions 1, 2,
   and 3 respectively. Be sure to crossover TX and RX.
3. Copy RAM firmware image
   openwrt-qualcommax-ipq807x-tplink_eap660hd-v1-initramfs-uImage.itb
   to TFTP server root, available at 192.168.10.1.
4. Connect PoE ethernet cable to the RJ45 port and hold Ctrl+B in the
   serial console (115200 baud) until autoboot is halted.
5. Run the following commands in the U-boot prompt:
   # tftpboot 0x44000000 openwrt-qualcommax-ipq807x-tplink_eap660hd-v1-initramfs-uImage.itb
   # bootm
   You may need to type Ctrl+C and Enter before running these commands
   to clear invisible characters from the buffer.
6. Run the following command in a terminal to copy the sysupgrade image
   to be installed (check IP address):
   $ scp openwrt-qualcommax-ipq807x-tplink_eap660hd-v1-squashfs-sysupgrade.bin root@192.168.1.1:/tmp/
7. Activate the OpenWrt serial console and run the following commands:
   # cd /tmp
   # sysupgrade -n openwrt-qualcommax-ipq807x-tplink_eap660hd-v1-squashfs-sysupgrade.bin
8. The AP will reboot and OpenWrt will be successfully installed.

Signed-off-by: George Witt <george.witt@nltsproject.org>
Link: https://github.com/openwrt/openwrt/pull/15832
Signed-off-by: Robert Marko <robimarko@gmail.com>