selftest/bpf: Fix error usage of ASSERT_OK in xdp_adjust_tail.c

xdp_adjust_tail.c calls ASSERT_OK() to check the return value of
bpf_prog_test_load(), but the condition is not correct. Fix it.

Fixes: 791cad02 ("bpf: selftests: Get rid of CHECK macro in xdp_adjust_tail.c")
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/bpf/20221011120108.782373-7-xukuohai@huaweicloud.com

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

@@ -18,7 +18,7 @@ static void test_xdp_adjust_tail_shrink(void)
 	);
 
 	err = bpf_prog_test_load(file, BPF_PROG_TYPE_XDP, &obj, &prog_fd);
-	if (ASSERT_OK(err, "test_xdp_adjust_tail_shrink"))
+	if (!ASSERT_OK(err, "test_xdp_adjust_tail_shrink"))
 		return;
 
 	err = bpf_prog_test_run_opts(prog_fd, &topts);
@@ -53,7 +53,7 @@ static void test_xdp_adjust_tail_grow(void)
 	);
 
 	err = bpf_prog_test_load(file, BPF_PROG_TYPE_XDP, &obj, &prog_fd);
-	if (ASSERT_OK(err, "test_xdp_adjust_tail_grow"))
+	if (!ASSERT_OK(err, "test_xdp_adjust_tail_grow"))
 		return;
 
 	err = bpf_prog_test_run_opts(prog_fd, &topts);
@@ -90,7 +90,7 @@ static void test_xdp_adjust_tail_grow2(void)
 	);
 
 	err = bpf_prog_test_load(file, BPF_PROG_TYPE_XDP, &obj, &prog_fd);
-	if (ASSERT_OK(err, "test_xdp_adjust_tail_grow"))
+	if (!ASSERT_OK(err, "test_xdp_adjust_tail_grow"))
 		return;
 
 	/* Test case-64 */