[HLSL][DirectX] Fix updateBufferCounter signature

[joaosaffran]

updateBufferCounter needs to return uint with the pre-incremented or pre-decremented counter value:

See https://godbolt.org/z/rGhWbcrY5
https://learn.microsoft.com/en-us/windows/win32/direct3dhlsl/sm5-object-rwstructuredbuffer-incrementcounter