Fix waitForNetwork

TinyGsmClient.h

@@ -339,10 +339,12 @@ public:
       RegStatus s = getRegistrationStatus();
       if (s == REG_OK_HOME || s == REG_OK_ROAMING) {
         return true;
+      } else if (s == REG_UNREGISTERED) {
+        return false;
       }
       delay(1000);
     }
-    return true;
+    return false;
   }
 
   /*