usb: gadget: legacy: dbgp: eliminate abuse of ep->driver data

Since ep->driver_data is not used for endpoint claiming, neither for
enabled/disabled state storing, we can reduce number of places where
we read or modify it's value, as now it has no particular meaning for
function or framework logic.

In case of dbgp, ep->driver_data was used only for endpoint claiming
and marking endpoints as enabled, so we can simplify code by reducing
it.

Signed-off-by: Robert Baldyga <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/gadget/legacy/dbgp.c

···
 
 static void __disable_ep(struct usb_ep *ep)
 {
-	if (ep && ep->driver_data == dbgp.gadget) {
-		usb_ep_disable(ep);
-		ep->driver_data = NULL;
-	}
+	usb_ep_disable(ep);
 }
 
 static void dbgp_disable_ep(void)
···
 	int err;
 	ep->desc = desc;
 	err = usb_ep_enable(ep);
-	ep->driver_data = dbgp.gadget;
 	return err;
 }
 
···
 		usb_ep_free_request(gadget->ep0, dbgp.req);
 		dbgp.req = NULL;
 	}
-
-	gadget->ep0->driver_data = NULL;
 }
 
 #ifdef CONFIG_USB_G_DBGP_SERIAL
···
 		goto fail_1;
 	}
 
-	dbgp.i_ep->driver_data = gadget;
 	i_desc.wMaxPacketSize =
 		cpu_to_le16(USB_DEBUG_MAX_PACKET_SIZE);
 
 	dbgp.o_ep = usb_ep_autoconfig(gadget, &o_desc);
 	if (!dbgp.o_ep) {
-		dbgp.i_ep->driver_data = NULL;
 		stp = 2;
-		goto fail_2;
+		goto fail_1;
 	}
 
-	dbgp.o_ep->driver_data = gadget;
 	o_desc.wMaxPacketSize =
 		cpu_to_le16(USB_DEBUG_MAX_PACKET_SIZE);
 
···
 
 	return 0;
 
-fail_2:
-	dbgp.i_ep->driver_data = NULL;
 fail_1:
 	dev_dbg(&dbgp.gadget->dev, "ep config: failure (%d)\n", stp);
 	return -ENODEV;
···
 	}
 
 	dbgp.req->length = DBGP_REQ_EP0_LEN;
-	gadget->ep0->driver_data = gadget;
 
 #ifdef CONFIG_USB_G_DBGP_SERIAL
 	dbgp.serial = kzalloc(sizeof(struct gserial), GFP_KERNEL);
···
 	int err = -EOPNOTSUPP;
 	void *data = NULL;
 	u16 len = 0;
-
-	gadget->ep0->driver_data = gadget;
 
 	if (request == USB_REQ_GET_DESCRIPTOR) {
 		switch (value>>8) {