Disable DTLS is UDP socket is disabled

The implementation of DTLS uses UDP socket.

Change-Id: I8be5c286a47abe9fa80a5a0e139dedc2f297992d
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

src/network/configure.json

@@ -292,7 +292,7 @@
             "label": "DTLS",
             "purpose": "Provides a DTLS implementation",
             "section": "Networking",
-            "condition": "features.openssl && tests.dtls",
+            "condition": "features.openssl && features.udpsocket && tests.dtls",
             "output": [ "publicFeature" ]
         },
         "ocsp": {