surfaceflinger: no re-saturation when in SRGB mode

Under ColorMode::SRGB and RenderIntent::ENHANCE, HWC always applies
the legacy sRGB saturation matrix.  SurfaceFlinger should not apply
the matrix.

Bug: 78891890
Test: no color shift when forcing GPU fallback
Change-Id: I7ebbefa38c5a6b72d326e0b2d4eee52d8409b5c7
1 file changed