[riscv64] Fix mjsunit/regexp-global fatal error

Change-Id: Ic36d34ca928b2dbc7427f60818dbd612b386e7a2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2967709


Reviewed-by: Ji Qiu <qiuji@iscas.ac.cn>
Commit-Queue: Ji Qiu <qiuji@iscas.ac.cn>
Cr-Commit-Position: refs/heads/master@{#75211}