USB: musb: mark expected switch fall-throughs

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

Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/musb/musb_dsps.c

···
 		}
 		musb_writeb(musb->mregs, MUSB_DEVCTL, 0);
 		skip_session = 1;
-		/* fall */
+		/* fall through */
 
 	case OTG_STATE_A_IDLE:
 	case OTG_STATE_B_IDLE:

drivers/usb/musb/musb_host.c

···
 				qh = first_qh(head);
 				break;
 			}
+			/* else: fall through */
 
 		case USB_ENDPOINT_XFER_ISOC:
 		case USB_ENDPOINT_XFER_INT: