ALSA: opti9xx: mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Addresses-Coverity-ID: 402016 ("Missing break in switch")
Addresses-Coverity-ID: 1056542 ("Missing break in switch")
Addresses-Coverity-ID: 1339579 ("Missing break in switch")
Addresses-Coverity-ID: 1369526 ("Missing break in switch")
Addresses-Coverity-ID: 1369529 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>

sound/isa/opti9xx/miro.c

···
 			switch (timeout-ACI_MINTIME) {
 			case 0 ... 9:
 				out /= 10;
+				/* fall through */
 			case 10 ... 19:
 				out /= 10;
+				/* fall through */
 			case 20 ... 30:
 				out /= 10;
+				/* fall through */
 			default:
 				set_current_state(TASK_UNINTERRUPTIBLE);
 				schedule_timeout(out);
···
 			retval = inb(chip->mc_base + 9);
 			break;
 		}
+		/* fall through */
 
 	case OPTi9XX_HW_82C929:
 		retval = inb(chip->mc_base + reg);
···
 			outb(value, chip->mc_base + 9);
 			break;
 		}
+		/* fall through */
 
 	case OPTi9XX_HW_82C929:
 		outb(value, chip->mc_base + reg);