scripts/kallsyms: update the usage in the comment block

commit 79549da6 upstream.

Commit 010a0aad ("kallsyms: Correctly sequence symbols when
CONFIG_LTO_CLANG=y") added --lto-clang, and updated the usage()
function, but not the comment. Update it in the same way.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>