Indicates the configured preference value assigned to the unit.
The preference value indicates how likely this unit is to be
chosen as the management unit. A value of 0 indicates a disabled
or unassigned preference. Setting this object to 0 will also set
agentInventoryUnitHWMgmtPref to unassigned(2). Setting this object
to a non-zero value will set agentInventoryUnitHWMgmtPref to
assigned(3). This value overrides the value of
agentInventoryUnitHWMgmtPref if assigned.