Fix Arma cheats still enterable under certain circumstances

Thanks to Epoch forums user Golgofinyanin for reporting.
https://epochmod.com/forum/profile/13156-golgofinyanin/

SQF/dayz_code/init/variables.sqf

@@ -713,4 +713,5 @@ if (!isDedicated) then {
 	DZE_InRadiationZone = false;
 	DZE_myVehicle = objNull;
 	dayz_groupNameTags = true;
+	dayz_minusDownTime = 0;
 };