selftest/net/ovpn: fix TCP socket creation

TCP sockets cannot be created with AF_UNSPEC, but
one among the supported family must be used.

Since commit 944f8b6 ("selftest/net/ovpn: extend
coverage with more test cases") the default address
family for all tests was changed from AF_INET to AF_UNSPEC,
thus breaking all TCP cases.

Restore AF_INET as default address family for TCP listeners.

Fixes: 944f8b6 ("selftest/net/ovpn: extend coverage with more test cases")
Signed-off-by: Antonio Quartulli <antonio@openvpn.net>

Author: ordex

tools/testing/selftests/net/ovpn/ovpn-cli.c

@@ -2166,6 +2166,7 @@ static int ovpn_parse_cmd_args(struct ovpn_ctx *ovpn, int argc, char *argv[])
 
 		ovpn->peers_file = argv[4];
 
+		ovpn->sa_family = AF_INET;
 		if (argc > 5 && !strcmp(argv[5], "ipv6"))
 			ovpn->sa_family = AF_INET6;
 		break;