net: hns3: fix use-after-free bug in hclgevf_send_mbx_msg

In the Linux kernel, the following vulnerability has been resolved: net: hns3: fix use-after-free bug in hclgevf_send_mbx_msg Currently, the hns3_remove function firstly uninstall client instance, and then uninstall acceletion engine device. The netdevice is freed in client instance uninstall process, but acceletion engine device uninstall process still use it to trace runtime information. This causes a use after free problem. So fixes it by check the instance register state to avoid use after free.