bpf: remove cg_skb_func_proto and use sk_filter_func_proto directly

Since cg_skb_func_proto() doesn't do anything else than just calling
into sk_filter_func_proto(), remove it and set sk_filter_func_proto()
directly for .get_func_proto callback.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/filter.c

@@ -2774,12 +2774,6 @@ xdp_func_proto(enum bpf_func_id func_id)
 	}
 }
 
-static const struct bpf_func_proto *
-cg_skb_func_proto(enum bpf_func_id func_id)
-{
-	return sk_filter_func_proto(func_id);
-}
-
 static const struct bpf_func_proto *
 lwt_inout_func_proto(enum bpf_func_id func_id)
 {
@@ -3344,7 +3338,7 @@ const struct bpf_verifier_ops xdp_prog_ops = {
 };
 
 const struct bpf_verifier_ops cg_skb_prog_ops = {
-	.get_func_proto		= cg_skb_func_proto,
+	.get_func_proto		= sk_filter_func_proto,
 	.is_valid_access	= sk_filter_is_valid_access,
 	.convert_ctx_access	= bpf_convert_ctx_access,
 	.test_run		= bpf_prog_test_run_skb,