usb: gadget: net22xx: fix ->disconnect reporting

with the latest udc_start/udc_stop conversion,
too much code was deleted which ended up creating
a regression in net2272 and net2280 drivers.

To fix the regression we revert one hunk of the
original commits.

Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/gadget/net2280.c b/drivers/usb/gadget/net2280.c
index a1b650e..3105a4d 100644
--- a/drivers/usb/gadget/net2280.c
+++ b/drivers/usb/gadget/net2280.c
@@ -1946,6 +1946,13 @@
 	for (i = 0; i < 7; i++)
 		nuke (&dev->ep [i]);
 
+	/* report disconnect; the driver is already quiesced */
+	if (driver) {
+		spin_unlock(&dev->lock);
+		driver->disconnect(&dev->gadget);
+		spin_lock(&dev->lock);
+	}
+
 	usb_reinit (dev);
 }