[graphite] Use SIMD half conversion in UniformManager

Change-Id: I3a641e1742287611e87c83fe24f96240a9e12151
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/801976
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Auto-Submit: Michael Ludwig <michaelludwig@google.com>
1 file changed