kernel-uboot: compress arm64 kernels
AArch64 images are not self-decompressing, thus usually much larger.
Boot times can be reduced by compressing them in FIT and uImages.
This commit is a backport of commit
a725d188b5 (kernel-uboot: compress
arm64 kernels) and commit
60bc7e180e (kernel-uboot: remove useless
special casing of arm64 Image) from master. Both commit were melted
into one to avoid some useless churn.
Signed-off-by: Alban Bedel <alban.bedel@aerq.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
