udev rule assigns insecure file permissions

[afaerber]

udev-50-tenstorrent.rules (referenced by dkms-post-install) assigns MODE="0666" to the device file.

This is considered insecure, as it gives not just human users but any system services/daemons (including web servers) write access to the hardware.

Better would be to assign MODE="0660" and optionally a suitable group. The users who should have access can then get that group assigned individually.

It's trivial to not install this rule in distro packages, but it would probably be good to fix this for dkms users, too.

[smehtaTT]

Nice to have - moving to P2 for now, will bump up to P1 if critical.