USB: 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/misc/appledisplay.c

···
 		dev_err(dev,
 			"OVERFLOW with data length %d, actual length is %d\n",
 			ACD_URB_BUFFER_LEN, pdata->urb->actual_length);
+		/* fall through */
 	case -ECONNRESET:
 	case -ENOENT:
 	case -ESHUTDOWN:

drivers/usb/renesas_usbhs/mod_gadget.c

···
 	case READ_STATUS_STAGE:
 	case WRITE_STATUS_STAGE:
 		usbhs_dcp_control_transfer_done(pipe);
+		/* fall through */
 	default:
 		return ret;
 	}