Add PerformanceLoss threshold checking

This xyz.openbmc_project.Sensor.Threshold.PerformanceLoss interface will
be checked along with the other threshold interfaces.  It can be used to
indicate the system will suffer a performance loss when the sensor goes
above/below the high/low threshold values.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: I855aaf6ea550e672bf52af5631533049269934d1
3 files changed