Lora band define (#1231)

main/config_LORA.h

@@ -36,7 +36,9 @@ extern void MQTTtoLORA(char* topicOri, JsonObject& RFdata);
 #define subjectGTWLORAtoMQTT "/LORAtoMQTT"
 
 //Default parameters used when the parameters are not set in the json data
-#define LORA_BAND             868E6
+#ifndef LORA_BAND
+#  define LORA_BAND 868E6
+#endif
 #define LORA_SIGNAL_BANDWIDTH 125E3
 #define LORA_TX_POWER         17
 #define LORA_SPREADING_FACTOR 7