RFR: 8355472: Clean up x86 nativeInst after 32-bit x86 removal

[Julian Waters]

On Mon, 28 Apr 2025 08:23:25 GMT, Manuel Hässig <duke at openjdk.org> wrote:

> This PR cleans up code 32-bit x86 code in `nativeInst_x86.*` files.
> 
> Testing:
>  - [x] tier1 through tier4 on x86 plus Oracle internal testing

Looks good

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Marked as reviewed by jwaters (Committer).

PR Review: https://git.openjdk.org/jdk/pull/24911#pullrequestreview-2798610740