staging: comedi: ni_labpc_cs: cleanup labpc_cs_attach()

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

Also, remove the dev_dbg() 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>