VideoBackends:D3D12: Don't query GPU descriptor handle for non-shader visible heap

Fixes the following error in the D3D12 debug layer:

D3D12 ERROR: ID3D12DescriptorHeap::GetGPUDescriptorHandleForHeapStart:
GetGPUDescriptorHandleForHeapStart is invalid to call on a descriptor
heap that does not have DESCRIPTOR_HEAP_FLAG_SHADER_VISIBLE set.
If the heap is not supposed to be shader visible, then
GetCPUDescriptorHandleForHeapStart would be the appropriate method
to call. That call is valid both for shader visible and non shader
visible descriptor heaps.
[ STATE_GETTING ERROR #1315: DESCRIPTOR_HEAP_NOT_SHADER_VISIBLE]

Source/Core/VideoBackends/D3D12/DescriptorHeapManager.cpp

@@ -25,7 +25,6 @@ bool DescriptorHeapManager::Create(ID3D12Device* device, D3D12_DESCRIPTOR_HEAP_T
     return false;
 
   m_heap_base_cpu = m_descriptor_heap->GetCPUDescriptorHandleForHeapStart();
-  m_heap_base_gpu = m_descriptor_heap->GetGPUDescriptorHandleForHeapStart();
   m_num_descriptors = num_descriptors;
   m_descriptor_increment_size = device->GetDescriptorHandleIncrementSize(type);
 
@@ -60,7 +59,7 @@ bool DescriptorHeapManager::Allocate(DescriptorHandle* handle)
 
     handle->index = index;
     handle->cpu_handle.ptr = m_heap_base_cpu.ptr + index * m_descriptor_increment_size;
-    handle->gpu_handle.ptr = m_heap_base_gpu.ptr + index * m_descriptor_increment_size;
+    handle->gpu_handle.ptr = 0;
     return true;
   }
 

Source/Core/VideoBackends/D3D12/DescriptorHeapManager.h

@@ -41,7 +41,6 @@ private:
   u32 m_descriptor_increment_size = 0;
 
   D3D12_CPU_DESCRIPTOR_HANDLE m_heap_base_cpu = {};
-  D3D12_GPU_DESCRIPTOR_HANDLE m_heap_base_gpu = {};
 
   static constexpr u32 BITSET_SIZE = 1024;
   using BitSetType = std::bitset<BITSET_SIZE>;