Staging: Beceem: use after free in bcm_exit()

We can't call class_destroy() until after the driver has been deregistered.
It leads to a NULL deref on module unload.
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/bcm/InterfaceInit.c

@@ -658,9 +658,8 @@ static __init int bcm_init(void)
 
 static __exit void bcm_exit(void)
 {
-	class_destroy(bcm_class);
-
 	usb_deregister(&usbbcm_driver);
+	class_destroy(bcm_class);
 }
 
 module_init(bcm_init);