Drop the factory images and the firmware tool to create them. They don't
work any more, since the factory image has an uImage header covering the
whole kernel + rootfs. This way the uImage splitter will not be able to
find the rootfs and the kernel will panic later on.
The factory images were most likely added at a time the board had
distinct partitions for kernel and rootfs.
Signed-off-by: Mathias Kresin <dev@kresin.me>