usb: gadget: f_phonet: mark expected switch fall-throughs

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

Addresses-Coverity-ID: 115004
Addresses-Coverity-ID: 115005
Signed-off-by: NGustavo A. R. Silva <garsilva@embeddedor.com>
Acked-by: NFelipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/f_phonet.c

@@ -215,6 +215,7 @@ static void pn_tx_complete(struct usb_ep *ep, struct usb_request *req)
 	case -ESHUTDOWN: /* disconnected */
 	case -ECONNRESET: /* disabled */
 		dev->stats.tx_aborted_errors++;
+		/* fall through */
 	default:
 		dev->stats.tx_errors++;
 	}
@@ -362,6 +363,7 @@ static void pn_rx_complete(struct usb_ep *ep, struct usb_request *req)
 	/* Do resubmit in these cases: */
 	case -EOVERFLOW: /* request buffer overflow */
 		dev->stats.rx_over_errors++;
+		/* fall through */
 	default:
 		dev->stats.rx_errors++;
 		break;