staging: comedi: ni_mio_cs: cleanup cs_attach()

Absorb the code from mio_cs_config() into this function and
properly return the error if the configuration fails.

Remove the DPRINTK() function trace message.

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>