Revert of Make GrGammaEffect have explicit sRGB modes, plus exponential mode. (patchset #4 id:60001 of https://codereview.chromium.org/1954863002/ )

Reason for revert:
Shader compilation appears to be failing

Original issue's description:
> Make GrGammaEffect have explicit sRGB modes, plus exponential mode.
>
> Convert it to a "standard" FP that just transforms the input color.
>
> For now, we still infer the sRGB transfer curves from the exponent,
> but I'm hoping that eventually SkGammas will provide us with the
> exact curve we're supposed to be applying. In any case, this adds
> support for doing the inverse transformation, as well, which will
> be needed in an upcoming Vulkan YUV change, among other things.
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1954863002
>
> Committed: https://skia.googlesource.com/skia/+/2139303e4c0a9cbcfac695977a80eb026a9296ab

TBR=bsalomon@google.com,brianosman@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review-Url: https://codereview.chromium.org/1964943003
3 files changed