RFR: 8283937: riscv: RVC: Fix c_beqz to c_bnez

[Xiaolin Zheng]

Hi team,

As the appointment (mentioned in #7982 ), submit another PR for reviews.

This patch fixes a typo introduced in [JDK-8278994](https://bugs.openjdk.java.net/browse/JDK-8278994): `c_bnez` is mistakenly written to `c_beqz`, though not used until now, needing a fix for future usage.

Thanks,
Xiaolin

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Commit messages:
 - Fix a typo instroduced when refactoring: c.beqz

Changes: https://git.openjdk.java.net/jdk/pull/8034/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8034&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8283937
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8034.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8034/head:pull/8034

PR: https://git.openjdk.java.net/jdk/pull/8034