RFR: 8308091: Remove unused iRegIHeapbase() matching operand [v2]

[Fei Yang]

On Tue, 16 May 2023 08:35:45 GMT, Xiaolin Zheng <xlinzheng at openjdk.org> wrote:

>> The `iRegIHeapbase()` matching operand has no usage on both AArch64 and RISC-V platforms after [JDK-8242449](https://bugs.openjdk.org/browse/JDK-8242449) and [JDK-8306667](https://bugs.openjdk.org/browse/JDK-8306667), respectively. As the following-up action discussed in the code review process of [JDK-8306667](https://bugs.openjdk.org/browse/JDK-8306667) (#13577), this is a small cleanup for the `iRegIHeapbase()` matching operand.
>> 
>> Passed fastdebug/release build on both AArch64/RISC-V platforms.
>> 
>> Thanks,
>> Xiaolin
>
> Xiaolin Zheng has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Further cleanups

Updated change LGTM. Thanks.

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Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/13983#pullrequestreview-1432671883