bpf: sockmap, fix double-free

`e' is being freed twice.

Fix this by removing one of the kfree() calls.

Addresses-Coverity-ID: 1468983 ("Double free")
Fixes: 81110384 ("bpf: sockmap, add hash map support")
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

kernel/bpf/sockmap.c

@@ -1823,7 +1823,6 @@ static int __sock_map_ctx_update_elem(struct bpf_map *map,
 	write_unlock_bh(&sock->sk_callback_lock);
 	return err;
 out_free:
-	kfree(e);
 	smap_release_sock(psock, sock);
 out_progs:
 	if (verdict)