selftests/bpf: Convert tcp_estats test to ASSERT_* macros

Convert the selftest to use the preferred ASSERT_* macros instead of the
deprecated CHECK().

Signed-off-by: Wang Yufen <[e-mail]>
Signed-off-by: Andrii Nakryiko <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/testing/selftests/bpf/prog_tests/tcp_estats.c

···
 	const char *file = "./test_tcp_estats.bpf.o";
 	int err, prog_fd;
 	struct bpf_object *obj;
-	__u32 duration = 0;
 
 	err = bpf_prog_test_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
-	CHECK(err, "", "err %d errno %d\n", err, errno);
-	if (err)
+	if (!ASSERT_OK(err, ""))
 		return;
 
 	bpf_object__close(obj);