staging: comedi: ni_mio_common: scale ao INSN_CONFIG_GET_CMD_TIMING_CONSTRAINTS

Fixes implementation of INSN_CONFIG_GET_CMD_TIMING_CONSTRAINTS for
ni_mio devices.  The previous patch should have used the channel
information passed in to scale the result by the number of channels being
used.

Fixes: 51fd3673 ("staging: comedi: ni_mio_common: implement INSN_CONFIG_GET_CMD_TIMING_CONSTRAINTS")
Signed-off-by: Spencer E. Olson <olsonse@umich.edu>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>