AntennaTracker: rename AP_AHRS::get_position to get_location

AntennaTracker/Tracker.cpp

@@ -96,7 +96,7 @@ void Tracker::one_second_loop()
     if (!ahrs.home_is_set()) {
         // set home to current location
         Location temp_loc;
-        if (ahrs.get_position(temp_loc)) {
+        if (ahrs.get_location(temp_loc)) {
             if (!set_home(temp_loc)){
                 // fail silently
             }

AntennaTracker/tracking.cpp

@@ -34,7 +34,7 @@ void Tracker::update_tracker_position()
     Location temp_loc;
 
     // REVISIT: what if we lose lock during a mission and the antenna is moving?
-    if (ahrs.get_position(temp_loc)) {
+    if (ahrs.get_location(temp_loc)) {
         stationary = false;
         current_loc = temp_loc;
     }