fix dshot: remove setAllFailsafeValues

Fixes a regression from c1e5e666f0,
where with static mixers the dshot outputs would go to max instead of 0
in a failsafe case.

src/drivers/dshot/DShot.cpp

@@ -47,7 +47,6 @@ DShot::DShot() :
 	_mixing_output.setAllDisarmedValues(DSHOT_DISARM_VALUE);
 	_mixing_output.setAllMinValues(DSHOT_MIN_THROTTLE);
 	_mixing_output.setAllMaxValues(DSHOT_MAX_THROTTLE);
-	_mixing_output.setAllFailsafeValues(UINT16_MAX);
 }
 
 DShot::~DShot()