The value of tmnxPtpClockPortState indicates the current state of the
single PTP port when tmnxPtpClockClockType is either
'ordinarySlave (1)' or 'ordinaryMaster (2)'. Otherwise,
tmnxPtpClockPortState is 'notApplicable (0)'.
The value of this object corresponds to the
portDS.portState data set member defined in IEEE Std 1588-2008.