RFR: 8321631: Fix comments in access.hpp

[Stefan Karlsson]

On Sat, 9 Dec 2023 07:59:02 GMT, Guoxiong Li <gli at openjdk.org> wrote:

> Hi all,
> 
> This trivial patch fixes the comments about `atomic_xchg` and `atomic_xchg_at` in `access.hpp`.
> And it removes the unnecessary content about `INSTANTIATE_HPP_ACCESS` 
> which has been aleready removed in [JDK-8230808](https://bugs.openjdk.org/browse/JDK-8230808).
> 
> Thanks for the review.
> 
> Best Regards,
> -- Guoxiong

Marked as reviewed by stefank (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/17042#pullrequestreview-1774768137