staging: comedi: adv_pci1710: tidy up analog input subdev_flags

Remove the SDF_COMMON flag, the analog reference is not programmable and
the default aref (AREF_GROUND -> SDF_GROUND) provides adequate information
about the reference.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: NIan Abbott <abbotti@mev.co.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/adv_pci1710.c

@@ -793,7 +793,7 @@ static int pci1710_auto_attach(struct comedi_device *dev,
 	/* Analog Input subdevice */
 	s = &dev->subdevices[subdev];
 	s->type		= COMEDI_SUBD_AI;
-	s->subdev_flags	= SDF_READABLE | SDF_COMMON | SDF_GROUND;
+	s->subdev_flags	= SDF_READABLE | SDF_GROUND;
 	if (!board->is_pci1711)
 		s->subdev_flags	|= SDF_DIFF;
 	s->n_chan	= board->is_pci1713 ? 32 : 16;