RFR: 8362284: RISC-V: cleanup NativeMovRegMem [v2]

[Fei Yang]

On Wed, 16 Jul 2025 10:48:23 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you help to review this simple patch?
>> 
>> NativeMovRegMem on riscv is actually dead code, but still needed in case of compilation of C1.
>> So make the code as simple as possible to avoid any reading and maintainance effort.
>> 
>> No tests, as `offset()` and `set_offset()` were Unimplemented and used in C1 and never triggered before.
>> 
>> Thanks!
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   use nullptr

Marked as reviewed by fyang (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/26328#pullrequestreview-3024690862