ALSA: pcsp: 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 letting the code fall
through to the next case.

Link: https://github.com/KSPP/linux/issues/115
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/9705120ac2310bb20035e375862410413359611d.1605896059.git.gustavoars@kernel.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/pcsp/pcsp_input.c

@@ -54,6 +54,7 @@ static int pcspkr_input_event(struct input_dev *dev, unsigned int type,
 		case SND_BELL:
 			if (value)
 				value = 1000;
+			break;
 		case SND_TONE:
 			break;
 		default: