[llvm] [M68k] Add support for bitwise NOT instruction (PR #88049)

[Peter Lafreniere via llvm-commits]

n8pjl wrote:

Thank you, and yes, I'll write a few tests for MC. I didn't know that those existed.
I did make sure that inline assembly works, but only for data register direct (it's the same with neg[x]).

Does LLVM have a preference over if the MC tests go into a second commit, or if I revise the first commit and force push?

https://github.com/llvm/llvm-project/pull/88049