AP_GPS: add SAVE_CFG parameter make ublox config saving optional

libraries/AP_GPS/AP_GPS.cpp

@@ -108,6 +108,13 @@ const AP_Param::GroupInfo AP_GPS::var_info[] = {
     // @RebootRequired: True
     AP_GROUPINFO("GNSS_MODE", 10, AP_GPS, _gnss_mode, 0),
 
+    // @Param: SAVE_CFG
+    // @DisplayName: Save GPS configuration
+    // @Description: Determines whether the configuration for this GPS should be written to non-volatile memory on the GPS. Currently working for UBlox.
+    // @Values: 0:Do not save config,1:Save config
+    // @User: Advanced
+    AP_GROUPINFO("SAVE_CFG", 11, AP_GPS, _save_config, 0),
+
     AP_GROUPEND
 };
 

libraries/AP_GPS/AP_GPS.h

@@ -317,6 +317,7 @@ public:
     AP_Int8 _min_elevation;
     AP_Int8 _raw_data;
     AP_Int8 _gnss_mode;
+    AP_Int8 _save_config;
     
     // handle sending of initialisation strings to the GPS
     void send_blob_start(uint8_t instance, const char *_blob, uint16_t size);

libraries/AP_GPS/AP_GPS_UBLOX.cpp

@@ -157,7 +157,7 @@ AP_GPS_UBLOX::read(void)
 
     if (need_rate_update) {
         send_next_rate_update();
-    }else if(!_cfg_saved) {         //save the configuration sent until now
+    }else if(!_cfg_saved && gps._save_config) {         //save the configuration sent until now
         _save_cfg();
     }