usb: gadget: u_serial: Set start_delayed during suspend

Upstream commit aba3a8d ("usb: gadget: u_serial: add suspend
resume callbacks") added started_delayed flag, so that new ports
which are opened after USB suspend can start IO while resuming.
But if the port was already opened, and gadget suspend kicks in
afterwards, start_delayed will never be set. This causes resume
to bail out before calling gs_start_io(). Fix this by setting
start_delayed during suspend.

Fixes: aba3a8d ("usb: gadget: u_serial: add suspend resume callbacks")
Cc: stable@vger.kernel.org
Signed-off-by: Prashanth K <quic_prashk@quicinc.com>
Link: https://lore.kernel.org/r/20240730125754.576326-1-quic_prashk@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/u_serial.c

@@ -1441,6 +1441,7 @@ void gserial_suspend(struct gserial *gser)
 	spin_lock(&port->port_lock);
 	spin_unlock(&serial_port_lock);
 	port->suspended = true;
+	port->start_delayed = true;
 	spin_unlock_irqrestore(&port->port_lock, flags);
 }
 EXPORT_SYMBOL_GPL(gserial_suspend);