staging: comedi: icp_multi: absorb setup_channel_list()

This function is only called in one place and the 'n_chan' parameter
is always 1. This makes the for() loop a bit silly.

Absorb the function into the caller and simplify the code. This also
removes the need for the private data member 'AdcCmdStatus'.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>