RFR: 8351861: RISC-V: add simple assert at arrays_equals_v

[Hamlin Li]

Hi,
Can you help to review this trivial patch?

`arrays_equals_v` and `arrays_equals` are 2 versions of the same node `AryEqNode`, input `elem_size` should be the same, so should share the same assert of `elem_size`, this also make the code below more clear.
Although at the same time, we could do the similar thing like https://github.com/openjdk/jdk/pull/24006, but as the code of `arrays_equals_v` and `arrays_equals` seems not require the input must be a byte[] (although in the java level a string's payload is indeed a byte[]), so I'll just leave if as is.

Thanks

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

Commit messages:
 - assert diff registers
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/24008/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24008&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351861
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/24008.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24008/head:pull/24008

PR: https://git.openjdk.org/jdk/pull/24008