This allows the user to set the preferred
member ID of a switch when stacking is enabled on
it. hpStackSwitchPreferredMemberId needs to be
set along with setting hpStackSwitchAdminStatus
being set to 'true (1)'. This entry is useful only
at the time of setting hpStackSwitchAdminStatus to
'true (1)'. hpStackSwitchPreferredMemberId is
unused when hpStackSwitchAdminStatus is set to
false (2).