RFR: 8374351: RISC-V: Small refactoring for crypto macro-assembler routines

[Anjian Wen]

This patch is mainly for readability and subsequent GCM call requirements.

1. Extract the ghash function to facilitate subsequent calls during the implementation of aes-gcm 
2. Unify the prefixes of function names for aes intrinsic-related functions. Only use generate prefix for the main intrinsic function, delete the other functions `generate_` prefix

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Commit messages:
 - RISC-V: extraction and reconstruction of the ghash loop function

Changes: https://git.openjdk.org/jdk/pull/28988/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28988&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8374351
  Stats: 73 lines in 1 file changed: 28 ins; 18 del; 27 mod
  Patch: https://git.openjdk.org/jdk/pull/28988.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28988/head:pull/28988

PR: https://git.openjdk.org/jdk/pull/28988