Sub: cleanup unused variable

ArduSub/joystick.cpp

@@ -54,8 +54,6 @@ void Sub::transform_manual_control_to_rc_override(int16_t x, int16_t y, int16_t
 
     int16_t channels[11];
 
-    uint32_t tnow_ms = millis();
-
     float rpyScale = 0.4*gain; // Scale -1000-1000 to -400-400 with gain
     float throttleScale = 0.8*gain*g.throttle_gain; // Scale 0-1000 to 0-800 times gain
     int16_t rpyCenter = 1500;