staging: comedi: ni_660x: checkpatch.pl cleanup (break not useful)

Fix the checkpatch.pl warnings:

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/ni_660x.c

@@ -619,10 +619,8 @@ static inline unsigned ni_660x_read_register(struct comedi_device *dev,
 	switch (registerData[reg].size) {
 	case DATA_2B:
 		return readw(read_address);
-		break;
 	case DATA_4B:
 		return readl(read_address);
-		break;
 	default:
 		BUG();
 		break;