[nrf fromtree] drivers: udc_dwc2: Fix memory leak on subsequent bus resets

Do not queue new buffer after bus reset if there is one already queued.
This fixes memory leak on each bus reset if there are no SETUP transfers
received between resets.

Signed-off-by: Tomasz Moń <[email protected]>
(cherry picked from commit c180420)

Author: tmon-nordic

drivers/usb/udc/udc_dwc2.c

@@ -434,6 +434,11 @@ static void dwc2_ensure_setup_ready(const struct device *dev)
 	} else {
 		struct udc_dwc2_data *const priv = udc_get_private(dev);
 
+		if (udc_ep_is_busy(udc_get_ep_cfg(dev, USB_CONTROL_EP_OUT))) {
+			/* There is already buffer queued */
+			return;
+		}
+
 		/* Enable EP0 OUT only if there is no pending EP0 IN transfer
 		 * after which the stack has to enable EP0 OUT.
 		 */