Fix missing generic.ins on s390x

commit 0c4e1955ee accidentally dropped the
generic.ins file from the iso. This restores that graft point to the
xorrisofs call.

Resolves: rhbz#2044448

80-rhel/s390.tmpl

@@ -83,6 +83,7 @@ runcmd xorrisofs ${isoargs} -o ${outroot}/images/boot.iso \
        -boot-load-size 4 -no-emul-boot \
        -R -J -V '${isolabel}' -graft-points \
        .discinfo=${outroot}/.discinfo \
+       generic.ins=${outroot}/generic.ins \
        ${BOOTDIR}=${outroot}/${BOOTDIR} \
        ${filegraft}
 treeinfo images-${basearch} boot.iso images/boot.iso