apparmor: Fix double free of ns_name in aa_replace_profiles()

In the Linux kernel, the following vulnerability has been resolved:

apparmor: Fix double free of ns_name in aa_replace_profiles()

if ns_name is NULL after

1071 error = aa_unpack(udata, &lh, &ns_name);

and if ent->ns_name contains an ns_name in

1089 } else if (ent->ns_name) {

then ns_name is assigned the ent->ns_name

1095 ns_name = ent->ns_name;

however ent->ns_name is freed at

1262 aa_load_ent_free(ent);

and then again when freeing ns_name at

1270 kfree(ns_name);

Fix this by NULLing out ent->ns_name after it is transferred to ns_name

")