Rover: Change delay method to HAL scheduler's delay

Rover/Rover.h

@@ -298,9 +298,6 @@ private:
     bool set_home(const Location& loc, bool lock) WARN_IF_UNUSED;
     void update_home();
 
-    // compat.cpp
-    void delay(uint32_t ms);
-
     // crash_check.cpp
     void crash_check();
 

Rover/system.cpp

@@ -137,7 +137,7 @@ void Rover::startup_ground(void)
 
     #if(GROUND_START_DELAY > 0)
         gcs().send_text(MAV_SEVERITY_NOTICE, "<startup_ground> With delay");
-        delay(GROUND_START_DELAY * 1000);
+        hal.scheduler->delay(GROUND_START_DELAY * 1000);
     #endif
 
     // IMU ground start