This effectively reverts commit 67acde4869.
After commits 569ad251ad and
67acde4869, -EACCES errors are ignored,
and thus 'udevadm trigger' succeeds even when it is invoked by non-root
users. Moreover, on -EACCES error, log messages are shown in debug
level, so usually we see no message, and users are easily confused
why uevents for devices are not triggered.