staging: comedi: cb_pcidas: cleanup cb_pcidas_ai_rinsn()

Create local variables for the channel, range, and aref in order
to make the remaining code a bit cleaner.

Remove the extra space in all the comments.

Remove the 'static const int timeout' and just use the open
coded value in the loop.

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