staging: comedi: ni_mio_common: remove deadcode in ni_ai_insn_config()

The previous mask by 0xf ensures that calib_source will not be > 0xf.
Remove the dead code.

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

drivers/staging/comedi/drivers/ni_mio_common.c

@@ -2732,9 +2732,6 @@ static int ni_ai_insn_config(struct comedi_device *dev,
 
 			calib_source = data[1] & 0xf;
 
-			if (calib_source > 0xF)
-				return -EINVAL;
-
 			devpriv->ai_calib_source = calib_source;
 			ni_writew(dev, calib_source, Calibration_Channel_6143);
 		} else {