Supporting ZSUN Wifi Card Reader (16MB Flash, 64MB RAM, AR9331)

@golfo I have no idea why it happened but copy all files from /staging_dir/target-mips_24kc_musl/ from SDK to imagebuilder works for me

@Magnets I bought from Tmart but it's sold out now. Buy from superbuy which helps to buy items from Taobao (by pasting the link example to Shopping Agent) may be a way.

@JuggernauT I add usb support to 18.06_rec, it seems works.

root@OpenWrt:~# block info
/dev/mtdblock2: UUID="05105fc9-29341dd5-9c8606df-dc19c9e2" VERSION="4.0" MOUNT="/rom" TYPE="squashfs"
/dev/mtdblock3: MOUNT="/overlay" TYPE="jffs2"
/dev/mtdblock8: UUID="05105fc9-29341dd5-9c8606df-dc19c9e2" VERSION="4.0" TYPE="squashfs"
/dev/sda1: UUID="3761-6664" LABEL="NO NAME" VERSION="FAT32" TYPE="vfat"
root@OpenWrt:~# mkdir /mnt/card
root@OpenWrt:~# mount /dev/sda1 /mnt/card/
root@OpenWrt:~# df -h /mnt/card/
Filesystem                Size      Used Available Use% Mounted on
/dev/sda1                14.8G      3.4M     14.8G   0% /mnt/card