d3d12: fix code after simple-shader helper changes
The changes in !7323 (merged) broke the D3D12 driver, and it wasn't noticed because it's not yet hooked up to the CI.
Let's fix the fallout, and try to get the CI bits in !7537 (merged) landed soon.
The changes in !7323 (merged) broke the D3D12 driver, and it wasn't noticed because it's not yet hooked up to the CI.
Let's fix the fallout, and try to get the CI bits in !7537 (merged) landed soon.