ipq806x/nbg6817: add support for ZyXEL NBG6817

ipq806x/nbg6817: add support for ZyXEL NBG6817

CPU: 2x1.8GHz ARM, RAM: 512MiB
Storage: 4MiB serial Flash, 3.9GiB MMC
NIC: 2x1GBit/s, Switch with 5 external and 2 internal ports
WiFi: Dualband, ath10k 2.4GHz, 5GHz MU-MIMO

For installation copy xx-mmcblk0p4-kernel.bin and xx-mmcblk0p5-rootfs-full.bin
to device. Then run:
cat xx-mmcblk0p4-kernel.bin > /dev/mmc0blk0p4
cat xx-mmcblk0p5-rootfs-full.bin > /dev/mmc0blk0p5
reboot -f

For debugging serial console is easily visible on board, no soldering needed.

Signed-off-by: André Valentin <avalentin@marcant.net>