ath79: support Dragino LPS8

ath79: support Dragino LPS8

Dragino LPS8 is a LoRa/LoRaWAN gateway with single Wi-Fi 4 radio and a
single Fast Ethernet port, based around Dragino HE module.

Specifications:
CPU: Atheros AR9330 SoC @400MHz,
RAM: 64MB DDR,
Flash: 16MB SPI-NOR,
Ethernet: One 100Mbps port.
Wireless: built-in 1x1 802.11 2.4GHz radio,
USB: single USB2.0 High speed host port,
LoRa: Semtech SX1301 or compatible module, dependent on LoRa band.
Power: USB-C 5V, with the usual 5,1k CC resistors missing - use type
A-to-C cable.

LEDs:
- LAN (red)
- WAN/Status (RGB, blue: status, green: WLAN, red: WAN)
- LoRa (bicolor, controlled by Semtech module)

UART: 3.3V 115200-8-N-1 at internal expansion header J2
RxD: pin 4
TxD: pin 6
GND: pin 8
Label MAC: Wi-Fi interface.

Installation:
Log in via SSH to the unit, default username and password are 'root' and
'dragino', respectively. SSH listens on port 2222.
Just 'sysupgrade -n' from vendor firmware, dropping old configuration.

Restore vendor firmware:
the same as installation, just 'sysupgrade -F -n', dropping configuration.

Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/23472
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>