ath79: add support for Hak5 WiFi Pineapple NANO

ath79: add support for Hak5 WiFi Pineapple NANO

Hak5 WiFi Pineapple NANO is an "USB dongle" device dedicated for Wi-Fi
pentesters. This device is based on Atheros AR9331 and AR9271. Support
for it was first introduced in 950b278c81 (ar71xx). FCC ID: 2AB87-NANO.

Specifications:

- Atheros AR9331
- 400/400/200 MHz (CPU/DDR/AHB)
- 64 MB of RAM (DDR1)
- 16 MB of flash (SPI NOR)
- 1T1R 2.4 GHz Wi-Fi (AR9331)
- 1T1R 2.4 GHz Wi-Fi (AR9271L), with ext. PA and LNA (Qorvo RFFM4203)
- 2x RP-SMA antenna connectors
- 1x USB 2.0 to 10/100 Ethernet bridge (ASIX AX88772A)
- integrated 4-port USB 2.0 HUB: Alcor Micro AU6259:
  - 1x USB 2.0
  - 1x microSD card reader (Genesys Logic GL834L)
  - Atheros AR9271L
- 1x LED, 1x button
- UART (4-pin, 2 mm pitch) header on PCB
- USB 2.0 Type-A plug for power and AX88772A

Flash instruction:

You can use sysupgrade image directly in vendor firmware which is based
on OpenWrt/LEDE.

Signed-off-by: Piotr Dymacz <pepe2k@gmail.com>