Sub: Remove wrapper around MAVLink send heartbeat

ArduSub/GCS_Mavlink.cpp

@@ -2,11 +2,6 @@
 
 #include "GCS_Mavlink.h"
 
-void Sub::gcs_send_heartbeat()
-{
-    gcs().send_message(MSG_HEARTBEAT);
-}
-
 /*
  *  !!NOTE!!
  *
@@ -815,7 +810,7 @@ void Sub::mavlink_delay_cb()
     uint32_t tnow = AP_HAL::millis();
     if (tnow - last_1hz > 1000) {
         last_1hz = tnow;
-        gcs_send_heartbeat();
+        gcs().send_message(MSG_HEARTBEAT);
         gcs().send_message(MSG_SYS_STATUS);
     }
     if (tnow - last_50hz > 20) {

ArduSub/Sub.h

@@ -476,7 +476,6 @@ private:
     float get_surface_tracking_climb_rate(int16_t target_rate, float current_alt_target, float dt);
     void update_poscon_alt_max();
     void rotate_body_frame_to_NE(float &x, float &y);
-    void gcs_send_heartbeat(void);
     void send_heartbeat(mavlink_channel_t chan);
 #if RPM_ENABLED == ENABLED
     void rpm_update();