[d3d11] Only use mapped buffer for images if bind flags are non-zero

We really shouldn't use the intermediate buffer for DYNAMIC images
that can only ever be used for copy commands, since the copies will
be redundant.

src/d3d11/d3d11_texture.cpp

@@ -415,6 +415,7 @@ namespace dxvk {
     //    writing the image to device-local image may be more efficient than
     //    reading its contents from host-visible memory.
     if (m_desc.Usage         == D3D11_USAGE_DYNAMIC
+     && m_desc.BindFlags     != 0
      && m_desc.TextureLayout != D3D11_TEXTURE_LAYOUT_ROW_MAJOR)
       return D3D11_COMMON_TEXTURE_MAP_MODE_BUFFER;