net/core/filter: fix unused-variable warning

Building with CONFIG_INET=n will show the warning below:
net/core/filter.c: In function ‘____bpf_getsockopt’:
net/core/filter.c:4048:19: warning: unused variable ‘tp’ [-Wunused-variable]
  struct tcp_sock *tp;
                   ^~
net/core/filter.c:4046:31: warning: unused variable ‘icsk’ [-Wunused-variable]
  struct inet_connection_sock *icsk;
                               ^~~~
Move the variable declarations inside the {} block where they are used.

Fixes: 1e215300 ("bpf: add TCP_SAVE_SYN/TCP_SAVED_SYN options for bpf_(set|get)sockopt")
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net/core/filter.c

@@ -4051,14 +4051,15 @@ static const struct bpf_func_proto bpf_setsockopt_proto = {
 BPF_CALL_5(bpf_getsockopt, struct bpf_sock_ops_kern *, bpf_sock,
 	   int, level, int, optname, char *, optval, int, optlen)
 {
-	struct inet_connection_sock *icsk;
 	struct sock *sk = bpf_sock->sk;
-	struct tcp_sock *tp;
 
 	if (!sk_fullsock(sk))
 		goto err_clear;
 #ifdef CONFIG_INET
 	if (level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) {
+		struct inet_connection_sock *icsk;
+		struct tcp_sock *tp;
+
 		switch (optname) {
 		case TCP_CONGESTION:
 			icsk = inet_csk(sk);