kernel-fitimage: use correct kernel image

kernel-fitimage: use correct kernel image

Even if initramfs_bundle_path was used, a wrong compression was reflected
in output its template file. Use linux.bin as universal kernel image.
The linux.bin file covers both cases because it's beying created from
vmlinux.

We know, that vmlinux is created inside compressed directory already,
so no external compression will be used.

Signed-off-by: Andrej Valek <andrej.valek@siemens.com>
Signed-off-by: Walter Schweizer <walter.schweizer@siemens.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Backport of 27fbbeaf972bb7e2535c1b23375cfa9d66b69db6 in master branch
Signed-off-by: Remi Peuvergne <remi.peuvergne@non.se.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>