Float32/64 abs operation should only clear the sign bit, but abs.s
and abs.d instructions of mips64r2 would convert nan to canonical
nan.

Change-Id: Ibbd05cdb3a73acfe0e532030d1815d262c3ac433
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2439768
Commit-Queue: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70214}