Re-add Perlin noise rounding workaround for Android Vulkan

Without this workaround the filters-turb-01-f.svg Gold images are very very wrong for the P30/MaliG76 for the vk config(s).

There are also some subtle-ish artifacts (~19/255 magnitude) on the GalaxyS7_G930FD/MaliT880 for the vk config(s) on the same SVG.

Bug: skia:14171
Change-Id: I6d774bc708fcb80e9739ad7879c3c18a52f4af64
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/664181
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
2 files changed