Difficult to make use of if not installed

Fixes: cd1bfd5e ("seabios: update bios and vgabios binaries")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 153936155938.28040.11513367417790075721.stgit@gimli.home
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>