[llvm] [X86] Fix 32-bit immediate assertion and convert into backend error (PR #123872)

[Phoebe Wang via llvm-commits]

phoebewang wrote:

If I read the code correctly, it not only emit error for 32-bit but also fix the bug in 64-bit. The title and description don't mention the latter?

https://github.com/llvm/llvm-project/pull/123872