Revert of Support Float32 output from SkColorSpaceXform (patchset #7 id:140001 of...

Revert of Support Float32 output from SkColorSpaceXform (patchset #7 id:140001 of https://codereview.chromium.org/2339233003/ )

Reason for revert:
Hitting an assert

Original issue's description:
> Support Float32 output from SkColorSpaceXform
>
> * Adds Float32 support to SkColorSpaceXform
> * Changes API to allows clients to ask for F32, updates clients to
>   new API
> * Adds Sk4f_load4 and Sk4f_store4 to SkNx
> * Make use of new xform in SkGr.cpp
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2339233003
> CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot
>
> Committed: https://skia.googlesource.com/skia/+/43d6651111374b5d1e4ddd9030dcf079b448ec47

TBR=brianosman@google.com,mtklein@google.com,scroggo@google.com,mtklein@chromium.org,bsalomon@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/2347473007