Backport 2 commits to fix black screen issue with Nvidia, introduced in xserver-21.1.2
If there is one platform device, which is not paused nor resumed, systemd_logind_vtenter() will never get called. This break suspend/resume, and switching to VT on system with Nvidia proprietary driver.
This is a regression introduced by f5bd0396
So now call systemd_logind_vtenter() if there are no paused platform devices.
Fix compilation error when built without logind/platform bus
This was introduced by commit 8eb1396d