staging: comedi: s526: checkpatch.pl cleanup (break not useful)

Fix the checkpatch.pl warning:

WARNING: break is not useful after a goto or return
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>

drivers/staging/comedi/drivers/s526.c

@@ -345,7 +345,6 @@ static int s526_gpct_insn_config(struct comedi_device *dev,
 
 	default:
 		return -EINVAL;
-		break;
 	}
 
 	return insn->n;