Input: spaceball - mark expected switch fall-throughs

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

Addresses-Coverity-ID: 114767
Addresses-Coverity-ID: 114768
Addresses-Coverity-ID: 114769
Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/joystick/spaceball.c

···
 				break;
 			}
 			spaceball->escape = 0;
+			/* fall through */
 		case 'M':
 		case 'Q':
 		case 'S':
···
 				spaceball->escape = 0;
 				data &= 0x1f;
 			}
+			/* fall through */
 		default:
 			if (spaceball->escape)
 				spaceball->escape = 0;
···
 			input_dev->keybit[BIT_WORD(BTN_A)] |= BIT_MASK(BTN_A) |
 				BIT_MASK(BTN_B) | BIT_MASK(BTN_C) |
 				BIT_MASK(BTN_MODE);
+			/* fall through */
 		default:
 			input_dev->keybit[BIT_WORD(BTN_0)] |= BIT_MASK(BTN_2) |
 				BIT_MASK(BTN_3) | BIT_MASK(BTN_4) |
 				BIT_MASK(BTN_5) | BIT_MASK(BTN_6) |
 				BIT_MASK(BTN_7) | BIT_MASK(BTN_8);
+			/* fall through */
 		case SPACEBALL_3003C:
 			input_dev->keybit[BIT_WORD(BTN_0)] |= BIT_MASK(BTN_1) |
 				BIT_MASK(BTN_8);