COREOS_EFI_SECUREBOOT_KEYDIR_HASH was intended to store a hash
of each file present in build/key in order to discard the sstate
cache on key changes. But this variables was wrongly always empty
due to a wrong check in a loop.
Checking for COREOS_EFI_SECUREBOOT_INSTALL_PUBKEY_IN_EFIDIR
was not done properly resulting of the key always being
installed inside the EFI partition.
We are now using efibootguard to provide a A/B boot path for
the kernel and the rootfs.
This commit remove some change for systemd/systemd-boot that are
not needed anymore and rework how we set the command line, as we
will need to have the command line argument of the kernel both
inside do_image_wic and in a future do_image_swu
Samuel Dolt