RFR: 8315070: RISC-V: Clean up platform dependent inline headers

[Robbin Ehn]

On Sat, 26 Aug 2023 11:55:57 GMT, Feilong Jiang <fjiang at openjdk.org> wrote:

> Hi team, please review this small clean-up changes.
> Inspired by [JDK-8267464](https://bugs.openjdk.org/browse/JDK-8267464), riscv port still has one place that includes platform-dependent inline header `assembler_riscv.inline.hpp`, it could be replaced with platform-independent header `asm/assembler.inline.hpp`.
> 
> Testing: 
> - [x] release build on linux-riscv64
> - [x] tier1 on linux-riscv64 with release build

Thank you!

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Marked as reviewed by rehn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/15437#pullrequestreview-1598057453