tiltrotor: reduce BACKTRANS_THROTTLE_DOWNRAMP_DUR_S from 1 to 0.5s

This affects how soon after a backtransition the vehicle has the
full hover controller running again. Specifically it reduces the
duration of the ramp down of the motors prior to tilting them.

Signed-off-by: Silvan Fuhrer <silvan@auterion.com>

src/modules/vtol_att_control/tiltrotor.cpp

@@ -46,7 +46,7 @@ using namespace matrix;
 using namespace time_literals;
 
 #define  FRONTTRANS_THR_MIN 0.25f
-#define BACKTRANS_THROTTLE_DOWNRAMP_DUR_S 1.0f
+#define BACKTRANS_THROTTLE_DOWNRAMP_DUR_S 0.5f;
 #define BACKTRANS_THROTTLE_UPRAMP_DUR_S 1.0f;
 #define BACKTRANS_MOTORS_UPTILT_DUR_S 1.0f;