getevent: print error message when failing to get event

For some reason we weren't saying what the error was here, which could
be useful. Also change the failure message slightly to distinguish
between failing to get inotify and evdev events.

Bug: 245989146
Test: m toolbox
Change-Id: I456aa53d008043ea2549024002f9b88ea8d2d2cf
1 file changed