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

[Gui Cao]

> 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

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/12425/files
  - new: https://git.openjdk.org/jdk/pull/12425/files/e468629e..a4a05c55

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12425&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12425&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12425.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12425/head:pull/12425

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