The OutputRegister shouldn't be overwritten, because it may be the same register
as InputRegister(1), which will be used later.

And remove the useless if-else in And32, Or32, Xor32.

Change-Id: I1f944b5b6acd5c183cef537524827b47a8cb0186
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1967092
Auto-Submit: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65438}