D3D11: Fixed crash when driver unloads when context is released.

src/renderer_d3d11.cpp

@@ -1598,7 +1598,6 @@ namespace bgfx { namespace d3d11
 			DX_RELEASE(m_annotation, 1);
 			DX_RELEASE(m_swapChain, 0);
 			DX_RELEASE(m_deviceCtx, 0);
-			DX_RELEASE(m_device, 0);
 
 			m_dxgi.shutdown();