ath79: add support for NEC Aterm WF1200CR

ath79: add support for NEC Aterm WF1200CR

NEC Aterm WF1200CR is a 2.4/5 GHz band 11ac (Wi-Fi 5) router, based on
QCA9561.

Specification:

- SoC		: Qualcomm Atheros QCA9561
- RAM		: DDR2 128 MiB (W971GG6SB-25)
- Flash		: SPI-NOR 8 MiB (MX25L6433FM2I-08G)
- WLAN		: 2.4/5 GHz 2T2R
  - 2.4 GHz	: QCA9561 (SoC)
  - 5 GHz	: QCA9888
- Ethernet	: 2x 10/100 Mbps
  - Switch	: QCA9561 (SoC)
- LEDs/Keys	: 8x/3x (2x buttons, 1x slide-switch)
- UART		: through-hole on PCB
  - JP1: Vcc, GND, NC, TX, RX from "JP1" marking
  - 115200n8
- Power		: 12 VDC, 0.9 A

Flash instruction using factory image (stock: < v1.3.2):

1. Boot WF1200CR normally with "Router" mode
2. Access to "http://192.168.10.1/" and open firmware update page
   ("ファームウェア更新")
3. Select the OpenWrt factory image and click update ("更新") button to
   perform firmware update
4. Wait ~150 seconds to complete flashing

Alternate flash instruction using initramfs image (stock: >= v1.3.2):

1. Prepare the TFTP server with the IP address 192.168.1.10 and place
   the OpenWrt initramfs image to the TFTP directory with the name
   "0101A8C0.img"
2. Connect serial console to WF1200CR
3. Boot WF1200CR and interrupt with any key after the message
   "Hit any key to stop autoboot:  2", the U-Boot starts telnetd after
   the message "starting telnetd server from server 192.168.1.1"
4. login the telnet (address: 192.168.1.1)
5. Perform the following commands to modify "bootcmd" variable
   temporary and check the value
   (to ignore the limitation of available commands, "tp; " command at
   the first is required as dummy, and the output of "printenv" is
   printed on the serial console)

   tp; set bootcmd 'set autostart yes; tftpboot'
   tp; printenv

6. Save the modified variable with the following command and reset
   device

   tp; saveenv
   tp; reset

7. The U-Boot downloads initramfs image from TFTP server and boots it
8. On initramfs image, download the sysupgrade image to the device and
   perform the following commands to erase stock firmware and sysupgrade

   mtd erase firmware
   sysupgrade <sysupgrade image>

9. After the rebooting by completion of sysupgrade, start U-Boot telnetd
   and login with the same way above (3, 4)
10. Perform the following commands to reset "bootcmd" variable to the
    default and reset the device

    tp; run seattle
    tp; reset

    (the contents of "seattle":
     setenv bootcmd 'bootm 0x9f070040' && saveenv)
11. Wait booting-up the device

Known issues:

- the following 6x LEDs are connected to the gpio controller on QCA9888
  chip and the implementation of control via the controller is missing in
  ath10k/ath10k-ct

  - "ACTIVE" (Red/Green)
  - "2.4GHz" (Red/Green)
  - "5GHz"   (Red/Green)

Note:

- after the version v1.3.2 of stock firmware, "offline update" by
  uploading image by user is deleted and the factory image cannot be
  used

- the U-Boot on WF1200CR doesn't configure the port-side LEDs on WAN/LAN
  and the configuration is required on OpenWrt

  - gpio-hog: set the direction of GPIO 14(WAN)/19(LAN) to output
  - pinmux: set GPIO 14/19 as switch-controlled LEDs

Signed-off-by: INAGAKI Hiroshi <musashino.open@gmail.com>