ar71xx: Compex WPJ563 support

Specification:
- SoC: Qualcomm Atheros QCA9563 (775 MHz, MIPS 74Kc)
- RAM: 128 MiB
- Storage: 16MB NOR flash
- Wireless: Built into QCA9563 (Dragonfly), PHY modes b/g/n, 3x3 MIMO
- Ethernet: 2x1G

Tested and working:
- ethernet / switch / lan / wan
- 2.4GHz SoC wifi
- PCIe
- leds
- buzzer

Ramload:
- tftpboot 0x84000000 lede-ar71xx-generic-wpj563-16M-initramfs-uImage.bin
- bootm 0x84000000

Install:
- tftpboot 0x80500000 lede-ar71xx-generic-wpj563-16M-squashfs-sysupgrade.bin
- erase 0x9f030000 +$filesize
- erase 0x9f680000 +1
- cp.b $fileaddr 0x9f030000 $filesize

Erasing 0x9f680000 is required because uboot defines
"bootcmd=bootm 0x9f680000 || bootm 0x9f030000", so it first tries to boot
the higher address. I think the 16 mb flash are intended to be used as
8+8mb for a fallback image. In my hardware only the lower address has a
bootable image. But to make sure future hardware will boot lede too, I
erase one block, so uboot will skip this address.

Signed-off-by: Christian Mehlis <christian@m3hlis.de>