Scripts/Deadmines: Fix issues reported by static analysis

Fix Coverity issue id 1022474

src/server/scripts/EasternKingdoms/Deadmines/instance_deadmines.cpp

@@ -61,6 +61,8 @@ class instance_deadmines : public InstanceMapScript
                 SetHeaders(DataHeader);
 
                 State = CANNON_NOT_USED;
+                CannonBlast_Timer = 0;
+                PiratesDelay_Timer = 0;
             }
 
             ObjectGuid FactoryDoorGUID;