Start running an ADC analog acquisition schedule. The actual hardware schedule
will be initiated by the next RegWr* command, and then the ADCs will acquire
their first sample after the scheduleOnset specified in SetAdcSchedule.
Note that every call to StartAdcSchedule must be preceeded by a call to
SetAdcSchedule (ie: multiple calls to StartAdcSchedule each require their own
call to SetAdcSchedule)).
See DatapixxAdc*Demo files for examples.