ath79: add Netgear WNDAP360

ath79: add Netgear WNDAP360

SoC: Atheros AR7161
RAM: DDR 128 MiB (hynix h5dU5162ETR-E3C)
Flash: SPI-NOR 8 MiB (mx25l6406em2i-12g)
WLAN: 2.4/5 GHz
2.4 GHz: Atheros AR9220
5 GHz: Atheros AR9223
Ethernet: 4x 10/100/1000 Mbps (Atheros AR8021)
LEDs/Keys: 2/2 (Internet + System LED, Mesh button + Reset pin)
UART: RJ45 9600,8N1
Power: 12 VDC, 1.0 A

Installation instruction:
0. Make sure you have latest original firmware (3.7.11.4)
1. Connect to the Serial Port with a Serial Cable RJ45 to DB9/RS232
   (9600,8N1)
   screen  /dev/ttyUSB0 9600,cs8,-parenb,-cstopb,-hupcl,-crtscts,clocal
2. Configure your IP-Address to 192.168.1.42
3. When device boots hit spacebar
3. Configure the device for tftpboot
   setenv ipaddr 192.168.1.1
   setenv serverip 192.168.1.42
   saveenv
4. Reset the device
   reset
5. Hit again the spacebar
6. Now load the image via tftp:
   tftpboot 0x81000000 INITRAMFS.bin
7. Boot the image:
   bootm 0x81000000
8. Copy the squashfs-image to the device.
9. Do a sysupgrade.

https://openwrt.org/toh/netgear/wndap360

The device should be converted from kmod-owl-loader to nvmem-cells in the
future. Nvmem cells were not working. Maybe ATH9K_PCI_NO_EEPROM is missing.
That is why this commit is still using kmod-owl-loader. In the future
the device tree may look like this:

&ath9k0 {
       nvmem-cells = <&macaddr_art_120c>, <&cal_art_1000>;
       nvmem-cell-names = "mac-address", "calibration";
};

&ath9k1 {
       nvmem-cells = <&macaddr_art_520c>, <&cal_art_5000>;
       nvmem-cell-names = "mac-address", "calibration";
};

&art {
	...
	cal_art_1000: cal@1000 {
		reg = <0x1000 0xeb8>;
	};

	cal_art_5000: cal@5000 {
		reg = <0x5000 0xeb8>;
	};
};

Signed-off-by: Nick Hainke <vincent@systemli.org>