staging: rtl8188eu: usb_ops_linux: mark expected switch fall-through

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

Addresses-Coverity-ID: 1077613
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/os_dep/usb_ops_linux.c

@@ -407,6 +407,7 @@ static void usb_read_port_complete(struct urb *purb, struct pt_regs *regs)
 		case -ENODEV:
 		case -ESHUTDOWN:
 			adapt->bSurpriseRemoved = true;
+			/* fall through */
 		case -ENOENT:
 			adapt->bDriverStopped = true;
 			RT_TRACE(_module_hci_ops_os_c_, _drv_err_, ("usb_read_port_complete:bDriverStopped=true\n"));