RFR: 8322195: RISC-V: Minor improvement of MD5 instrinsic [v2]

[Hamlin Li]

> Hi,
> Can you review this minor patch to improve MD5 instrinsic?
> Thanks!
> 
> ## Test
> 
> tests (`find test/ -iname "*md5*.java"`) passed.

Hamlin Li has updated the pull request incrementally with two additional commits since the last revision:

 - add space
 - Add some comment

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17123/files
  - new: https://git.openjdk.org/jdk/pull/17123/files/2b7855a8..606b6248

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17123&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17123&range=00-01

  Stats: 8 lines in 1 file changed: 7 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17123.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17123/head:pull/17123

PR: https://git.openjdk.org/jdk/pull/17123