apparmor: Fix memleak in alloc_ns()

In the Linux kernel, the following vulnerability has been resolved: apparmor: Fix memleak in alloc_ns() After changes in commit a1bd627b46d1 ("apparmor: share profile name on replacement"), the hname member of struct aa_policy is not valid slab object, but a subset of that, it can not be freed by kfree_sensitive(), use aa_policy_destroy() to fix it.