Revert "linux: Check for Logind first, then *Kit-s with UPower when detecting PM framework"

This reverts commit c70fa349c0a5c2392045dd00751f64391fbef2e2.
It was not wrong but it seems distributions are not yet ready and the logind
path for e.g. suspending is not as well implemented as the scripts called by
upower initiated power operations.
Merge pull request #5826 from fritsch/upower

Revert "linux: Check for Logind first, then *Kit-s with UPower when detecting PM framework"