ath79: add support for OCEDO Ursus

ath79: add support for OCEDO Ursus

SOC:   Qualcomm Atheros QCA9558
RAM:   128MB
FLASH: 16MB (Macronix MX25L12845EMI-10G)
WLAN1: QCA9558 2.4GHz 802.11bgn 3SS
WLAN2: QCA9880 5GHz 802.11ac 3SS
LED:   Power, LAN1, LAN2, 2.4GHz, 5GHz
Serial:Next to SPI Flash,
       Pinout is 3V3 - GND - TX - RX (Square Pin is 3V3)
       The Serial setting is 115200-8-N-1

INSTALLATION:

1. Serve an OpenWrt ramdisk image named "ursus.bin".
   Set your IP-address to 192.168.100.8/24.
2. Connect to the serial. Power up the device and interrupt
   the boot process.
3. Set the correct bootcmd with
   > setenv bootcmd run bootcmd_1
   > saveenv
4. Run
   > tftpboot 0x81000000 ursus.bin
   > bootm 0x81000000
5. Wait for OpenWrt to boot up.
6. Transfer OpenWrt sysupdate image and flash via sysupgrade.

Signed-off-by: Markus Scheck <markus.scheck1@gmail.com>
Tested-by: David Bauer <mail@david-bauer.net>
[whitespace fix, renamed LED labels and SoC type fix]
Signed-off-by: Petr Štetiar <ynezz@true.cz>