bbswitch_dev: disable runtime PM on removal

Call pm_runtime_forbid() to balance it with pm_runtime_allow(), this
ensures that the runtime usage counter before loading and after
unloading match.

bbswitch_dev.c

@@ -38,6 +38,7 @@ static void bbswitch_pci_remove(struct pci_dev *dev)
 {
     pm_runtime_get_noresume(&dev->dev);
     pm_runtime_dont_use_autosuspend(&dev->dev);
+    pm_runtime_forbid(&dev->dev);
 }
 
 static int bbswitch_runtime_suspend(struct device *dev) {