xhci: Fix xhci debugfs NULL pointer dereference in resume from hibernate

Free the virt_device and its debugfs_private member together.

When resuming from hibernate the .free_dev callback unconditionally
freed the debugfs_private member, but could leave virt_device intact.

This triggered a NULL pointer dereference after resume when usbmuxd
sent a USBDEVFS_SETCONFIGURATION ioctl to a device, trying to add a
endpoint debugfs entry to a already freed debugfs_private pointer.

Fixes: 02b6fdc2 ("usb: xhci: Add debugfs interface for xHCI driver")
Reported-by: Alexander Kappner <agk@godking.net>
Tested-by: Alexander Kappner <agk@godking.net>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci.c

@@ -3525,8 +3525,6 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 	struct xhci_slot_ctx *slot_ctx;
 	int i, ret;
 
-	xhci_debugfs_remove_slot(xhci, udev->slot_id);
-
 #ifndef CONFIG_USB_DEFAULT_PERSIST
 	/*
 	 * We called pm_runtime_get_noresume when the device was attached.
@@ -3555,8 +3553,10 @@ static void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
 	}
 
 	ret = xhci_disable_slot(xhci, udev->slot_id);
-	if (ret)
+	if (ret) {
+		xhci_debugfs_remove_slot(xhci, udev->slot_id);
 		xhci_free_virt_device(xhci, udev->slot_id);
+	}
 }
 
 int xhci_disable_slot(struct xhci_hcd *xhci, u32 slot_id)