[riscv-port-jdk17u:riscv-port] RFR: 8302776: RISC-V: Fix typo CSR_INSTERT to CSR_INSTRET

[Fei Yang]

On Wed, 12 Apr 2023 10:48:34 GMT, Gui Cao <gcao at openjdk.org> wrote:

> Please review this backport to riscv-port-jdk17u.
> Backport of [JDK-8302776](https://bugs.openjdk.org/browse/JDK-8302776).
> 
>  Applies cleanly, and build success.

Marked as reviewed by fyang (Lead).

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PR Review: https://git.openjdk.org/riscv-port-jdk17u/pull/42#pullrequestreview-1381266939