selftests/bpf: Reuse the tcp_sk() from the bpf_tracing_net.h

This patch removes the individual tcp_sk implementations from the
tcp-cc tests. The tcp_sk() implementation from the bpf_tracing_net.h
is reused instead.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240509175026.3423614-4-martin.lau@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/progs/tcp_ca_incompl_cong_ops.c

 // SPDX-License-Identifier: GPL-2.0
 
-#include "vmlinux.h"
-
+#include "bpf_tracing_net.h"
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 
 char _license[] SEC("license") = "GPL";
 
-static inline struct tcp_sock *tcp_sk(const struct sock *sk)
-{
-	return (struct tcp_sock *)sk;
-}
-
 SEC("struct_ops/incompl_cong_ops_ssthresh")
 __u32 BPF_PROG(incompl_cong_ops_ssthresh, struct sock *sk)
 {

tools/testing/selftests/bpf/progs/tcp_ca_update.c

 // SPDX-License-Identifier: GPL-2.0
 
-#include "vmlinux.h"
-
+#include "bpf_tracing_net.h"
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 
@@ -10,11 +9,6 @@ char _license[] SEC("license") = "GPL";
 int ca1_cnt = 0;
 int ca2_cnt = 0;
 
-static inline struct tcp_sock *tcp_sk(const struct sock *sk)
-{
-	return (struct tcp_sock *)sk;
-}
-
 SEC("struct_ops/ca_update_1_init")
 void BPF_PROG(ca_update_1_init, struct sock *sk)
 {

tools/testing/selftests/bpf/progs/tcp_ca_write_sk_pacing.c

 // SPDX-License-Identifier: GPL-2.0
 
-#include "vmlinux.h"
-
+#include "bpf_tracing_net.h"
 #include <bpf/bpf_helpers.h>
 #include <bpf/bpf_tracing.h>
 
@@ -11,11 +10,6 @@ char _license[] SEC("license") = "GPL";
 
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
-static inline struct tcp_sock *tcp_sk(const struct sock *sk)
-{
-	return (struct tcp_sock *)sk;
-}
-
 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
 {
 	return tp->sacked_out + tp->lost_out;