kirkwood/dockstar: use ubi(kernel, squashfs, ubifs) images

The new image requires `bootz` because of devicetree appending.
To flash a new image boot initramfs:

  tftpboot 0x800000 openwrt-kirkwood-dockstar-initramfs-kernel.bin
  bootz 0x800000

  # detach if already attached
  ubidetach -p /dev/$(grep ubi /proc/mtd|awk -F: '{print $1}')
  # scp openwrt-kirkwood-dockstar-squashfs-factory.bin /tmp
  ubiformat -f /tmp/openwrt-kirkwood-dockstar-squashfs-factory.bin
  # attach is important to resize rootfs_data otherwise it wont boot
  ubiattach -p /dev/$(grep ubi /proc/mtd|awk -F: '{print $1}')

Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@49010 3c298f89-4303-0410-b956-a3cf2f4a3e73