[llvm] [ARM] Fix warnings in ARMAsmParser.cpp and ARMDisassembler.cpp (PR #112507)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

I had a patch to address this, I was sitting on it for a while whilst it was in the queue of commits. I think this should be using ARM::NoRegister instead of 0, which should fix the warning too without the need for the cast.

https://github.com/llvm/llvm-project/pull/112507