bpf, selftests: Fix test_maps now that sockmap supports UDP

UDP socket support was added recently so testing UDP insert failure is no
longer correct and causes test_maps failure. The fix is easy though, we
simply need to test that UDP is correctly added instead of blocked.

Fixes: 122e6c7 ("sock_map: Update sock type checks for UDP")
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210720184832.452430-1-john.fastabend@gmail.com

tools/testing/selftests/bpf/test_maps.c

@@ -764,8 +764,8 @@ static void test_sockmap(unsigned int tasks, void *data)
 	udp = socket(AF_INET, SOCK_DGRAM, 0);
 	i = 0;
 	err = bpf_map_update_elem(fd, &i, &udp, BPF_ANY);
-	if (!err) {
-		printf("Failed socket SOCK_DGRAM allowed '%i:%i'\n",
+	if (err) {
+		printf("Failed socket update SOCK_DGRAM '%i:%i'\n",
 		       i, udp);
 		goto out_sockmap;
 	}