ath79: add support for Winchannel WB2000

WB2000 is a dual-band 11N AP using AR9344.
The factory firmware used the original DB120 partition table
with a small kernel partition at the end of firmware and the
kernel will easily get oversized in the future. Since it has
to be flashed using UART I also swapped kernel/rootfs and
changed the default load address.

Specification:

- SoC: Atheros AR9344
- RAM: 128 MB
- Flash: 16 MB
- Ethernet: 10/100/1000 Mbps (Atheros AR8035)
- 2x USB 2.0
- WIFI: AR9344(2G) + AR9382(5G)
- RTC: DS1338

Known issue:
5G ath9k led doesn't work due to commit ccab68f.

Flash instruction:
Set up a TFTP server on your computer and configure static IP.
Connect UART (J11 TX/GND/RX) and press any key to enter U-boot
shell.
1. Change the default boot command:
   setenv bootcmd 'bootm 0x9f050000 || bootm 0x9fd50000'
   saveenv
2. Set your router ipaddr and server ipaddr. e.g.:
   setenv ipaddr 192.168.1.1
   setenv serverip 192.168.1.50
3. Load and flash the firmware:
   tftp 0x80060000 fw.bin
   erase 0x9f050000 +$filesize
   cp.b $fileaddr 0x9f050000 $filesize
4. Reset your router:
   reset

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
[Drop the i2c node unit address. Move the ath9k-leds node out of the spi
node, it doesn't belong there. Add the #gpio-cells property to the pci
wifi node. All fix dtc compiler warnings]
Signed-off-by: Mathias Kresin <dev@kresin.me>

merge

target/linux/ath79/base-files/etc/hotplug.d/firmware/10-ath9k-eeprom

@@ -127,7 +127,8 @@ case "$FIRMWARE" in
 	ocedo,raccoon|\
 	tplink,tl-wdr3600|\
 	tplink,tl-wdr4300|\
-	tplink,tl-wdr4900-v2)
+	tplink,tl-wdr4900-v2|\
+	winchannel,wb2000)
 		ath9k_eeprom_extract "art" 20480 1088
 		;;
 	netgear,wnr612-v2|\