Allocate RTDispatchGlobals as unboxed array

Previously we used an array-of-pointers approach, but using an
array-of-structures is in some ways simpler.

We also split out the RTStack as a separate allocation.

Related-To: LOCI-2966

Signed-off-by: Jim Snow <jim.m.snow@intel.com>

shared/source/device/device.h

@@ -41,10 +41,8 @@ struct EngineGroupT {
 using EngineGroupsT = std::vector<EngineGroupT>;
 
 struct RTDispatchGlobalsInfo {
-    RTDispatchGlobalsInfo(GraphicsAllocation *rtDispatchGlobalsArrayAllocation)
-        : rtDispatchGlobalsArrayAllocation(rtDispatchGlobalsArrayAllocation){};
-    std::vector<GraphicsAllocation *> rtDispatchGlobals;  // per tile
-    GraphicsAllocation *rtDispatchGlobalsArrayAllocation; // above array as visible from device
+    GraphicsAllocation *rtDispatchGlobalsArray = nullptr;
+    std::vector<GraphicsAllocation *> rtStacks; // per tile
 };
 
 class Device : public ReferenceTrackedObject<Device> {