Remove special case for DCI P3 when making ICC profiles

1) Almost nothing is ever DCI P3, cameras and such use Display P3
2) This transfer function was wrong: DCI P3's TF is gamma 2.6

Bug: skia:6720
Change-Id: I167a3ce40ff2296f4afb446408f691d300dacd9c
Reviewed-on: https://skia-review.googlesource.com/c/180378
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
2 files changed