[minor] unused cgroup permission string in device specs ?

[oOraph]

issue: the hardcoded "rwm" is not used and could be misleading

fix proposal here:
#1539

[elezar]

@oOraph we have merged the changes and released these as v1.19.0~rc.2. I'm closing the issue for now, but please reopen if you think this needs to be revisted.