ipq807x: add Edimax CAX1800

ipq807x: add Edimax CAX1800

Edimax CAX1800 is a 802.11 ax dual-band AP
with PoE. AP can be ceiling or wall mount.

Specifications:

    •     CPU: Qualcomm IPQ8070A Quad core Cortex-A53 1.4GHz
    •     RAM: 512MB of DDR3
    •     Storage: 128MB NAND (contains rootfs) / 8MB NOR (contains art and uboot-env)
    •     Ethernet: 1x 1G RJ45 port (QCA8072) PoE
    •     WLAN:
          2.4GHz: Qualcomm QCN5024 2x2 802.11b/g/n/ax 574 Mbps PHY rate
          5GHz: Qualcomm QCN5054 2x2 802.11a/b/g/n/ac/ax 1201 PHY rate

    •     LEDs:
          3 x GPIO-controlled System-LEDs
          (form one virtual RGB System-LED)
            black_small_square  Buttons: 1x soft reset
            black_small_square  Power: 12V DC jack or PoE (802.3af )

        An unpopulated serial header is onboard.
        RX/TX is working, bootwait is active, secure boot is not enabled.

        SSH can be activated in the stock firmware, but it drops only
        to a limited shell .

        Installation Instructions:

            black_small_square obtain serial access
            black_small_square stop auto boot

            black_small_square tftpboot the initramfs image (serverip is set to 192.168.99.8 in uboot)
            black_small_square bootm

            black_small_square copy openwrt-ipq807x-generic-edimax_cax1800-squashfs-nand-factory.ubi
	      to the device
            black_small_square write the image to the NAND:
            black_small_square cat /proc/mtd and look for rootfs partition (should be mtd0)
            black_small_square ubiformat /dev/mtd0 -f -y  openwrt-ipq807x-generic-edimax_cax1800-squashfs-
              nand-factory.ubi
            black_small_square reboot

	Note: Device is not using dual partitioning (NAND contains other partitions
        with different manufacture data etc.)
	Draytek VigorAP 960C and Lancom LW-600 both look similar, but I haven't checked them.

Signed-off-by: Dirk Buchwalder <buchwalder@posteo.de>