selftests: net:reuseaddr_conflict: fix success message formatting

Before:

    # selftests: net: reuseaddr_conflict
    # Opening 127.0.0.1:9999
    # Opening INADDR_ANY:9999
    # bind: Address already in use
    # Opening in6addr_any:9999
    # Opening INADDR_ANY:9999
    # bind: Address already in use
    # Opening INADDR_ANY:9999 after closing ipv6 socket
    # bind: Address already in use
    # Successok 5 selftests: net: reuseaddr_conflict

After:

    # selftests: net: reuseaddr_conflict
    # Opening 127.0.0.1:9999
    # Opening INADDR_ANY:9999
    # bind: Address already in use
    # Opening in6addr_any:9999
    # Opening INADDR_ANY:9999
    # bind: Address already in use
    # Opening INADDR_ANY:9999 after closing ipv6 socket
    # bind: Address already in use
    # Success
    ok 5 selftests: net: reuseaddr_conflict

Author: pvts-mat

tools/testing/selftests/net/reuseaddr_conflict.c

@@ -109,6 +109,6 @@ int main(void)
 	fd1 = open_port(0, 1);
 	if (fd1 >= 0)
 		error(1, 0, "Was allowed to create an ipv4 reuseport on an already bound non-reuseport socket with no ipv6");
-	fprintf(stderr, "Success");
+	fprintf(stderr, "Success\n");
 	return 0;
 }