SWDEV-289250 - Should return a nullptr for PAL so we can assume it's a host ptr

Change-Id: I530eb39104bbe727c3e38186f6db4e64285b3fc8

rocclr/device/device.hpp

@@ -1834,7 +1834,6 @@ class Device : public RuntimeObject {
   void SetActiveWait(bool state) { activeWait_ = state; }
 
   virtual amd::Memory* GetArenaMemObj(const void* ptr, size_t& offset) {
-    ShouldNotReachHere();
     return nullptr;
   }