Add ostree=aboot for signed Android Boot Images

Add ostree=aboot for signed Android Boot Images

Some kernel images are delivered in a signed kernel + cmdline +
initramfs + dtb blob. When this is added to the commit server side, only
after this do you know what the cmdline is, this creates a recursion
issue. To avoid this, in the case where we have ostree=aboot karg
set, create a symlink after deploy to the correct ostree target in the
rootfs, as the cmdline can't be malleable and secured client-side at
the same time.