Input: pcspkr - fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning
by explicitly adding a break statement instead of just letting the code
fall through to the next case.
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/4b659e3e65f2fa3c8bb7ed153e2016c3fb395bbc.1605896059.git.gustavoars@kernel.orgSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/misc/pcspkr.c

@@ -33,6 +33,7 @@ static int pcspkr_event(struct input_dev *dev, unsigned int type,
 	case SND_BELL:
 		if (value)
 			value = 1000;
+		break;
 	case SND_TONE:
 		break;
 	default: