staging: comedi: comedi_test: checkpatch.pl cleanup (break is 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/comedi_test.c

@@ -146,10 +146,8 @@ static unsigned short fake_waveform(struct comedi_device *dev,
 	switch (channel) {
 	case SAWTOOTH_CHAN:
 		return fake_sawtooth(dev, range, current_time);
-		break;
 	case SQUARE_CHAN:
 		return fake_squarewave(dev, range, current_time);
-		break;
 	default:
 		break;
 	}