RFR: 8301818: RISC-V: Factor out function mvw from MacroAssembler [v2]

[Feilong Jiang]

On Sat, 4 Feb 2023 11:30:03 GMT, Gui Cao <gcao at openjdk.org> wrote:

>> HI,
>> 
>> The two functions of mvw and mv overlap, we can use mv to replace mvw, so the mvw function can be removed. and format some code.
>> ## Testing:
>> - all tier1 on unmatched board without new failures
>
> Gui Cao has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Revert use lwu

Marked as reviewed by fjiang (Author).

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PR: https://git.openjdk.org/jdk/pull/12425