pc-bios/s390: Rebuild the s390x firmware images with the boot menu changes

Provide a new s390-ccw.img binary with the boot menu patches by Collin.
Though there should not be any visible changes for the network booting,
the s390-netboot.img binary has been rebuilt, too, since some of the
changes affected the shared source files.

Signed-off-by: Thomas Huth <thuth@redhat.com>