AP_DAL: remove unused antenna_offset state

libraries/AP_DAL/AP_DAL_GPS.cpp

@@ -49,8 +49,5 @@ void AP_DAL_GPS::start_frame()
 
         WRITE_REPLAY_BLOCK_IFCHANGED(RGPI, RGPI, old_RGPI);
         WRITE_REPLAY_BLOCK_IFCHANGED(RGPJ, RGPJ, old_RGPJ);
-
-        // also fetch antenna offset for this frame
-        antenna_offset[i] = gps.get_antenna_offset(i);
     }
 }

libraries/AP_DAL/AP_DAL_GPS.h

@@ -145,6 +145,4 @@ private:
     struct log_RGPH _RGPH;
     struct log_RGPI _RGPI[GPS_MAX_INSTANCES];
     struct log_RGPJ _RGPJ[GPS_MAX_INSTANCES];
-
-    Vector3f antenna_offset[GPS_MAX_INSTANCES];
 };