Sub: Fix control_manual compile warnings.

ArduSub/control_manual.cpp

@@ -18,9 +18,6 @@ bool Sub::manual_init(bool ignore_checks)
 // should be called at 100hz or more
 void Sub::manual_run()
 {
-    float target_roll, target_pitch, target_yaw;
-    float pilot_throttle_scaled;
-
     // if not armed set throttle to zero and exit immediately
     if (!motors.armed() || !motors.get_interlock()) {
         motors.set_desired_spool_state(AP_Motors::DESIRED_SPIN_WHEN_ARMED);