fix swapping of unipolar and bipolar postgain offsets during calibration
fix swapping of unipolar and bipolar postgain offsets during calibration

olsonse/comedilib,olsonse/comedilib,Linux-Comedi/comedilib,Linux-Comedi/comedilib,olsonse/comedilib,Linux-Comedi/comedilib,olsonse/comedilib,Linux-Comedi/comedilib,olsonse/comedilib,Linux-Comedi/comedilib,olsonse/comedilib,Linux-Comedi/comedilib