add protected mqtt_eth port, keep mqtt_port as-is

Author: brentru

src/AdafruitIO.h

@@ -78,6 +78,7 @@ class AdafruitIO {
 
     const char *_host = "io.adafruit.com";
     uint16_t _mqtt_port = 8883;
+    uint16_t _mqtt_eth_port = 1883;
     uint16_t _http_port = 443;
 
     uint16_t _packetread_timeout;

src/AdafruitIO_Ethernet.h

@@ -32,8 +32,7 @@ class AdafruitIO_Ethernet : public AdafruitIO
   AdafruitIO_Ethernet(const char *user, const char *key) : AdafruitIO(user, key)
   {
     _client = new EthernetClient();
-    uint16_t _eth_mqtt_port = 8883;
-    _mqtt = new Adafruit_MQTT_Client(_client, _host, _eth_mqtt_port, _username, _key);
+    _mqtt = new Adafruit_MQTT_Client(_client, _host, _mqtt_eth_port, _username, _key);
     _http = new HttpClient(*_client, _host, _http_port);
   }