initramfs-ostree-image: add cpio.gz.u-boot to IMAGE_FSTYPES
initramfs-ostree-image: add cpio.gz.u-boot to IMAGE_FSTYPES

Signed-off-by: Ming Liu <070ee461bca4578ddd34d91eec07d1f455f3cdee@gmail.com>

fluxos-iot/meta-flux,fluxos-iot/meta-flux,fluxos-iot/meta-flux