Increase precision of csc uniforms on ganesh

In particular, PQ's transfer function requires really high precision,
so using halfs instead of floats creates artifacts on some GPUs.

Bug: b/278122024
Change-Id: If403103f6f420588869aad00b228e81dd838e94e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/687083
Commit-Queue: Alec Mouri <alecmouri@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
(cherry picked from commit 1c2d2876434874d9bbdbaf25daca5a7c48dacbfa)
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/688178
1 file changed