USB: dbgp gadget: fix return value of dbgp_setup

Current code returns 0 even if it can't handle the request.
This leads to timeouts when an unhandled request is sent:

Bus 001 Device 003: ID 0525:c0de Netchip Technology, Inc.
Device Descriptor:
[..]
can't get device qualifier: Connection timed out
[..]

change the code to return EOPNOTSUPP in such cases.
Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/dbgp.c

@@ -350,9 +350,9 @@ static int dbgp_setup(struct usb_gadget *gadget,
 	u8 request = ctrl->bRequest;
 	u16 value = le16_to_cpu(ctrl->wValue);
 	u16 length = le16_to_cpu(ctrl->wLength);
-	int err = 0;
-	void *data;
-	u16 len;
+	int err = -EOPNOTSUPP;
+	void *data = NULL;
+	u16 len = 0;
 
 	gadget->ep0->driver_data = gadget;
 
@@ -371,10 +371,9 @@ static int dbgp_setup(struct usb_gadget *gadget,
 		default:
 			goto fail;
 		}
+		err = 0;
 	} else if (request == USB_REQ_SET_FEATURE &&
 		   value == USB_DEVICE_DEBUG_MODE) {
-		len = 0;
-		data = NULL;
 		dev_dbg(&dbgp.gadget->dev, "setup: feat debug\n");
 #ifdef CONFIG_USB_G_DBGP_PRINTK
 		err = dbgp_enable_ep();