To trigger the physical link diagnosis operation between
the Master device and the current selected EP device.
The traffic will be ceased during the diagnosis.
The diagnosed results may include the SNR/LineRate/PacketErrorRate/RxPower
for both the DnLink:'Transmit'(Tx)-to-EP and
UpLink:'Receive'(Rx)-from-EP operation.
The SNMP manager can set this value to activate(1) to
start the diagnosis procedure. The status (eocBrEPPhyDiagStatus)
will go from inProgress(1) status back to the initial
normalOrComplete(0) status.