[llvm] Set MaxAtomicSizeInBitsSupported for remaining targets. (PR #75703)

[James Y Knight via llvm-commits]

jyknight wrote:

Since this change makes LLVM consistent with what already happens in the Clang frontend for MSP430, I think it makes most sense to submit this, and do such an effort of reconsidering how it should work as a future task.

I'm happy to file a bug and assign it to you if you like (or reference such a bug in the commit description if you file it).

https://github.com/llvm/llvm-project/pull/75703