usb: gadget: f_serial: 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 f_serial, 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 <r.baldyga@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/function/f_serial.c

@@ -153,7 +153,7 @@ static int gser_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
 
 	/* we know alt == 0, so this is an activation or a reset */
 
-	if (gser->port.in->driver_data) {
+	if (gser->port.in->enabled) {
 		dev_dbg(&cdev->gadget->dev,
 			"reset generic ttyGS%d\n", gser->port_num);
 		gserial_disconnect(&gser->port);
@@ -219,13 +219,11 @@ static int gser_bind(struct usb_configuration *c, struct usb_function *f)
 	if (!ep)
 		goto fail;
 	gser->port.in = ep;
-	ep->driver_data = cdev;	/* claim */
 
 	ep = usb_ep_autoconfig(cdev->gadget, &gser_fs_out_desc);
 	if (!ep)
 		goto fail;
 	gser->port.out = ep;
-	ep->driver_data = cdev;	/* claim */
 
 	/* support all relevant hardware speeds... we expect that when
 	 * hardware is dual speed, all bulk-capable endpoints work at
@@ -249,12 +247,6 @@ static int gser_bind(struct usb_configuration *c, struct usb_function *f)
 	return 0;
 
 fail:
-	/* we might as well release our claims on endpoints */
-	if (gser->port.out)
-		gser->port.out->driver_data = NULL;
-	if (gser->port.in)
-		gser->port.in->driver_data = NULL;
-
 	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
 
 	return status;