udev-node: always atomically create symlink to device node

udev-node: always atomically create symlink to device node

By the previous commit, it is not necessary to distinguish if the devlink
already exists. Also, I cannot find any significant advantages of the
previous complecated logic, that is, first try to create directly, and then
fallback to atomically creation. Moreover, such logic increases the chance
of conflicts between multiple udev workers.

This makes devlinks always created atomically. Hopefully, this reduces the
conflicts between the workers.