The PD policy only applies to the situation that when a new
PD is inserted, and the power of PSE is overload.
A value of priority(2) means that the power will stop supplying
to the low priority port PD. About port priority, please refer
to pethPsePortPowerPriority. A value of disabled(1) means that
the slot stop supplying to the new inserted PD. The default
value of this object is disabled(1).