AP_Terrain: log_terrain_data no longer takes a DataFlash argument

libraries/AP_Terrain/AP_Terrain.cpp

@@ -340,7 +340,7 @@ void AP_Terrain::update(void)
 /*
   log terrain data to dataflash log
  */
-void AP_Terrain::log_terrain_data(DataFlash_Class &dataflash)
+void AP_Terrain::log_terrain_data()
 {
     if (!allocate()) {
         return;
@@ -370,7 +370,7 @@ void AP_Terrain::log_terrain_data(DataFlash_Class &dataflash)
         pending        : pending,
         loaded         : loaded
     };
-    dataflash.WriteBlock(&pkt, sizeof(pkt));
+    DataFlash_Class::instance()->WriteBlock(&pkt, sizeof(pkt));
 }
 
 /*

libraries/AP_Terrain/AP_Terrain.h

@@ -169,7 +169,7 @@ public:
     /*
       log terrain status to DataFlash
      */
-    void log_terrain_data(DataFlash_Class &dataflash);
+    void log_terrain_data();
 
     /*
       get some statistics for TERRAIN_REPORT