selinux: add the processing of the failure of avc_add_xperms_decision()

When avc_add_xperms_decision() fails, the information recorded by the new
avc node is incomplete. In this case, the new avc node should be released
instead of replacing the old avc node.

Cc: stable@vger.kernel.org
Fixes: fa1aa143 ("selinux: extended permissions for ioctls")
Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>