Fix needing to click lock/unlock twice from inside vehicle to take effect

No reason to use spawn here. Spawn can have a delay. Since
fn_selfActions runs faster it can register the vehicle as still locked
or unlocked after you clicked the action.

SQF/dayz_code/init/variables.sqf

@@ -687,4 +687,5 @@ if (!isDedicated) then {
 	DZE_Surrender = false;
 	DZE_Quarantine = false;
 	DZE_InRadiationZone = false;
+	DZE_myVehicle = objNull;
 };