With the introduction of the 6.5 kernel for mantic on 13th September ago we are seeing image build failures
on the armhf builds. The build failure was `No kernel output for generic-lpae!`.
Introduced in the 6.4 kernel and therefore now also in 6.5 there is no generic-lpae flavor anymore. it's just generic now.
As such this commit updates the expected flavour for armhf to generic.
Due to how `disk-image` file is structured, it builds BIOS and UEFI
images at the same time. However, certain images (e.g., GCE images)
require only UEFI image to be built, BIOS image is being simply
discarded. This results in longer build times.
Splitting out `disk-image-uefi` would allow images to use it instead of
`disk-image` and thus avoid building unused BIOS images.
`disk-image` now depends on `disk-image-uefi` for backward
compatibility.
