AP_DDS: fixed cell voltages #31521

Job	Run time
build (chibios, Durandal)	19m 44s
build (chibios, MatekF405)	18m 36s
build (chibios, KakuteF7)	17m 5s
build (chibios, MatekH743-bdshot)	20m 1s
build (chibios, Pixhawk1-1M)	17m 56s
build (chibios, MatekF405-CAN)	4m 18s
build (chibios, DrotekP3Pro)	3m 57s
build (chibios, Hitec-Airspeed)	5m 23s
build (chibios, f103-GPS)	5m 33s
build (disco, armhf)	16m 8s
	2h 8m 41s

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