staging: comedi: comedi_test: make timer rate similar to scan rate
The asynchronous command handling for the analog input subdevice uses a
kernel timer which expires approximately `HZ` times a second. However,
it only needs to do anything after each scan period. Set the timer to
expire just after the next scan period.
Although the timer expiry function `waveform_ai_interrupt()` uses
precise time values to generate the fake waveforms used to generate the
data, those time values are constructed in a precise sequence, and do
not depend on the time the timer expiry function is actually called. So
the timer expiry rate does not have to be very precise.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>