layerscape: ls1012afrdm: introduce dynamic partitioning

layerscape: ls1012afrdm: introduce dynamic partitioning

Combine fixed sizes of "kernel" and "rootfs" partitions into one
partition managed by OpenWrt splitter, it will allow better management
of chip capacity and less maintenance burden when compiled kernel image
will outgrow allocated size for kernel partition. This also changes kernel
image format, since splitter only manages kernel and rootfs partitions,
the dtb needs to be updated with the kernel, so for convenience, kernel is
packed to FIT image.

Signed-off-by: Tomasz Maciej Nowak <tomek_n@o2.pl>