Adding Dataspace BT2020_SRGB and ColorMode BT2020_SRGB

BT2020_SRGB is BT2020 with SRGB transfer function.  Adding to types V1.2
and upgrading methods that utilize Dataspace and ColorMode

Bug: 115335239
Test: ./libsurfaceflinger_unittest --gtest_filter=GetBestColorMode.*
Change-Id: Ic807183ae2bd0212cd8c5d7a24c93db0a1bc28fb
15 files changed