[llvm] [NFC][MC][XCore] Eliminate forward decls by rearranging functions (PR #155456)

[Rahul Joshi via llvm-commits]

jurahul wrote:

Note: I am ignoring the code formatter failure here to not do any additional formatting changes beyond moving functions around. Maybe we can do this in a later PR.

https://github.com/llvm/llvm-project/pull/155456