staging: comedi: ni_atmio16d: use comedi_timeout()

Use comedi_timeout() to wait for the analog input end-of-conversion.

Change the errno returned when the conversion overflows from -ETIME
to -EOVERFLOW.

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>