usb: wusbcore: wa-xfer: mark expected switch fall-through

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

Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/wusbcore/wa-xfer.c

@@ -2156,6 +2156,7 @@ static void wa_complete_remaining_xfer_segs(struct wa_xfer *xfer,
 		 * do not increment RPIPE avail for the WA_SEG_DELAYED case
 		 * since it has not been submitted to the RPIPE.
 		 */
+		/* fall through */
 		case WA_SEG_DELAYED:
 			xfer->segs_done++;
 			current_seg->status = status;