ath79: add support for DomyWifi DW33D

ath79: add support for DomyWifi DW33D

This commit ports the device from ar71xx to the ath79 target and
modifies the partition layout.
1. Firmware is installed to nand flash.
2. Modify the uboot-env parameter to boot from the nand flash.
3. The kernel size is extended to 5M.
4.nor flash retains the oem firmware.

oem partition layout
dev:    size   erasesize  name
mtd0: 00040000 00010000 "u-boot"
mtd1: 00010000 00010000 "u-boot-env"
mtd2: 00e30000 00010000 "rootfs"
mtd3: 00170000 00010000 "kernel"
mtd4: 00010000 00010000 "art"
mtd5: 00f90000 00010000 "firmware"
mtd6: 06000000 00020000 "rootfs_data"
mtd7: 02000000 00020000 "backup"

new partition layout
dev:    size   erasesize  name
mtd0: 00040000 00010000 "u-boot"
mtd1: 00010000 00010000 "u-boot-env"
mtd2: 00fa0000 00010000 "oem-firmware"
mtd3: 00010000 00010000 "art"
mtd4: 00500000 00020000 "kernel"
mtd5: 05b00000 00020000 "ubi"
mtd6: 02000000 00020000 "oem-backup"

MAC address overview:
All mac addresses are stored in the art partition.
eth0: 0x0
eth1: 0x6
ath9k: 0xc
ath10k: 0x12
No valid addresses in 0x1002 and 0x5006. All addresses match the OEM
firmware.

Install from oem firmware.
Enable ssh service:
Connect to the router web, click professional, click system-startup,
and add dropbear in the local startup input box. Click
system-administration, delete ssh-key, and replace your ssh pub key.
Restart the router.
1.Upload openwrt firmware to the device
scp openwrt-snapshot-r11365-df60a0852c-ath79-nand-domywifi_dw33d-\
squashfs-factory.bin root@192.168.10.1:/tmp
2.modify uboot-env.
ssh login to the device:
fw_setenv bootcmd 'nboot 0x8050000 0;bootm || bootm 0x9fe80000'
Run the fw_printenv command to check if the settings are correct.
3.Write openwrt firmware.
ssh login to the device:
mtd -r write /tmp/openwrt-snapshot-r11365-df60a0852c-ath79-nand-\
domywifi_dw33d-squashfs-factory.bin /dev/mtd6
The device will restart automatically and the openwrt firmware
installation is complete.

Restore oem firmware.just erase the kernel partition and the ubi
partition.
ssh login to the device:
mtd erase /dev/mtd4
mtd -r erase /dev/mtd5
Reboot the device

Signed-off-by: WeiDong Jia <jwdsccd@gmail.com>
[alter flash instruction in commit message]
Signed-off-by: Chuanhong Guo <gch981213@gmail.com>