Make ARGB32 blitting more consistent on loongarch codepath.

This patch is ported from [1] and it can fix
SkARGB32Blitter_MaskAndAntiHDrawTheSame test failed.
[1] https://skia-review.googlesource.com/c/skia/+/953516

Bug: b/397749778
Change-Id: Ie74e1b3e3cf5b7c47083376355296dd180a36610
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1006816
Reviewed-by: Florin Malita <fmalita@google.com>
Reviewed-by: Kaylee Lubick <kjlubick@google.com>
Commit-Queue: Florin Malita <fmalita@google.com>
Commit-Queue: Kaylee Lubick <kjlubick@google.com>