[llvm] [DirectX][ObectYAML] Make `RootParameterOffset` and `StaticSamplersOffset` behaviour consistent (PR #155521)

[Rainer Orth via llvm-commits]

rorth wrote:

This patch seems to have broken the [Solaris/sparcv9 buildbot](https://lab.llvm.org/buildbot/#/builders/13/builds/9273) badly.

https://github.com/llvm/llvm-project/pull/155521