Make the timedelta sensor appear right when a device is plugged-in, with a status of SENSOR_S_UNKNOWN.  Do not set the SENSOR_FINVALID bit, sysctl hw.sensors does not list sensors with this flags set and we want to the sensor when the device is present.
Make the timedelta sensor appear right when a device is plugged-in, with a
status of SENSOR_S_UNKNOWN.  Do not set the SENSOR_FINVALID bit, sysctl
hw.sensors does not list sensors with this flags set and we want to the sensor
when the device is present.

ok henning

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars