This object specify which port in the pair of
redundancy to be used as prefer port.
The value of:
primaryPort(1) is telling the system use the port
referred by c64PortConfigModule1Index,
c64PortConfigSubModule1Index and
c64PortConfigPort1Index as preferred port.
secondaryPort(2) is to use the port referred by
c64PortConfigModule2Index,
c64PortConfigSubModule2Index and
c64PortConfigPort2Index.
The default is primaryPort(1).