rpm/kernel-binary.spec.in: add explicit dependency of kernel-*-devel on
    libelf-devel. Otherwise warning that got turned into error by e683952999
    ("objtool: Upgrade libelf-devel warning to error...") would trigger and
    cause any packages being built against kernel-*-devel (such as KMPs,
    crash) not to have the libelf dependency included, and fail to build.