ath79: add support for ZyXEL NWA1123-AC

Specifications:
 * AR9342, 16 MiB Flash, 64 MiB RAM, 802.11n 2T2R, 2.4 GHz
 * QCA9882 PCIe card, 802.11ac 2T2R
 * 1x Gigabit Ethernet (AR8035), 802.3af PoE

Installation:
* OEM Web UI is at 192.168.1.2
  login as `admin` with password `1234`
* Flash factory-AAOX.bin

The string `AAOX` needs to be present within the file name of the uploaded
image to be accepted by the OEM Web-based updater, the factory image is
named accordingly to save the user from the hassle of manual renaming.

TFTP Recovery:
* Open the case, connect to TTL UART port (this is the official method
  described by Zyxel, the reset button is useless during power-on)
* Extract factory image (.tar.bz2), serve `vmlinux_mi124_f1e.lzma.uImage`
  and `mi124_f1e-jffs2` via tftp at 192.168.1.10
* Interrupt uboot countdown, execute commands
  `run lk`
  `run lf`
  to flash the kernel / filesystem accordingly

MAC addresses as verified by OEM firmware:
use   address   source
LAN   *:1c      mib0 0x30 ('eth0mac'), art 0x1002 (label)
2g    *:1c      mib0 0x4b ('wifi0mac')
5g    *:1e      mib0 0x66 ('wifi1mac')

Signed-off-by: Sebastian Schaper <openwrt@sebastianschaper.net>

target/linux/ath79/generic/base-files/etc/board.d/02_network

@@ -111,6 +111,7 @@ ath79_setup_interfaces()
 	wd,mynet-wifi-rangeextender|\
 	winchannel,wb2000|\
 	zyxel,nwa1121-ni|\
+	zyxel,nwa1123-ac|\
 	zyxel,nwa1123-ni)
 		ucidef_set_interface_lan "eth0"
 		;;

target/linux/ath79/generic/base-files/etc/hotplug.d/ieee80211/10_fix_wifi_mac

@@ -68,6 +68,10 @@ case "$board" in
 		[ "$PHYNBR" -eq 1 ] && \
 			mtd_get_mac_ascii u-boot-env ethaddr > /sys${DEVPATH}/macaddress
 		;;
+	zyxel,nwa1123-ac)
+		[ "$PHYNBR" -eq 0 ] && \
+			mtd_get_mac_text mib0 0x66 > /sys${DEVPATH}/macaddress
+		;;
 	zyxel,nwa1123-ni)
 		[ "$PHYNBR" -eq 1 ] && \
 			mtd_get_mac_text mib0 0x66 > /sys${DEVPATH}/macaddress