usb: gadget: gadgetfs: correct dev state

This reverts commit 1826e9b1 (usb: gadget: gadgetfs: use
after free in dev_release()) and places the call to
put_dev() after setting the state.

If this is not the final call to dev_release() and the
state is not reset to STATE_DEV_DISABLED and hence all
further open() calls to the gadgetfs ep0 device will
fail with EBUSY.
Signed-off-by: Marcus Nutzinger <marcus.nutzinger@theobroma-systems.com>
Reviewed-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/inode.c

@@ -1264,8 +1264,13 @@ dev_release (struct inode *inode, struct file *fd)
 
 	kfree (dev->buf);
 	dev->buf = NULL;
-	put_dev (dev);
 
+	/* other endpoints were all decoupled from this device */
+	spin_lock_irq(&dev->lock);
+	dev->state = STATE_DEV_DISABLED;
+	spin_unlock_irq(&dev->lock);
+
+	put_dev (dev);
 	return 0;
 }