depmod: Don't insert comment in modules.devname if otherwise empty
depmod: Don't insert comment in modules.devname if otherwise empty

This allows tools to detect the file as empty, such as via systemd's
ConditionFileNotEmpty.

lucasdemarchi/kmod,pmmccorm/kmod,lpereira/kmod,lpereira/kmod,pmmccorm/kmod,lpereira/kmod,pmmccorm/kmod,lucasdemarchi/kmod,lucasdemarchi/kmod