[riscv-port-jdk17u:riscv-port] RFR: 8305112: RISC-V: Typo fix for RVC description

[Xiaolin Zheng]

Backport the trivial typo fix in the RVC description, mentioned in #28.

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Commit messages:
 - 8305112: RISC-V: Typo fix for RVC description

Changes: https://git.openjdk.org/riscv-port-jdk17u/pull/30/files
 Webrev: https://webrevs.openjdk.org/?repo=riscv-port-jdk17u&pr=30&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305112
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/riscv-port-jdk17u/pull/30.diff
  Fetch: git fetch https://git.openjdk.org/riscv-port-jdk17u.git pull/30/head:pull/30

PR: https://git.openjdk.org/riscv-port-jdk17u/pull/30