Invert state of :PLCDISBITS00 and :PLCDISBITS01 for PowerPMAC to match TurboPMAC Readback

[JamesOHeaDLS]

m-variables m5000..m032 report the running state of PLCs on both Turbo and Power PMACs. However on TurboPMAC a value of 1 indicates PLC disabled, whereas on Power PMAC a value of 1 indicates PLC enabled.

This means that the pmacController screen displays the wrong state for PowerPMAC PLCs, and also affects the input to separate tools such as DeltaTauPLCStat. This module gets the state of PLCs from the pmac driver's PVs (as opposed to requesting the state from the controller directly)

The driver should change the sense of the PVs served depending on whether it is talking to a Turbo/PowerPMAC controller