LZMA compression makes about 33% smaller zImage
with just a slight extra decompression time.

Before this patch, zImage built with o2+_dc
is 4.5MiB and after it's about 3.3MiB.
Suggested-by: NDavid Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>