Revert "Add Ganesh support for RGBA_16161616 and RG_half"

This reverts commit 156622513ffc385bb493eda8d4cf5cbed19350d1.

Reason for revert: valgrind

Original change's description:
> Add Ganesh support for RGBA_16161616 and RG_half
> 
> Change-Id: Ia424ff719c5fb8d1842a909ade09ad6f5f78f21f
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/219998
> Reviewed-by: Greg Daniel <egdaniel@google.com>
> Commit-Queue: Robert Phillips <robertphillips@google.com>

TBR=egdaniel@google.com,robertphillips@google.com

Change-Id: I7a8e99e70f575fb301ce289d9a04ebbec25b934b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/220739
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/GrSurfaceContext.cpp b/src/gpu/GrSurfaceContext.cpp
index 32048c3..71113b4 100644
--- a/src/gpu/GrSurfaceContext.cpp
+++ b/src/gpu/GrSurfaceContext.cpp
@@ -72,11 +72,9 @@
         case GrColorType::kRG_F32:           return false;
         case GrColorType::kRGBA_F32:         return true;
         case GrColorType::kRGB_ETC1:         return false;
+        // Experimental (for P016 and P010)
         case GrColorType::kR_16:             return false;
         case GrColorType::kRG_1616:          return false;
-        // Experimental (for Y416 and mutant P016/P010)
-        case GrColorType::kRGBA_16161616:    return false;
-        case GrColorType::kRG_half:          return false;
     }
     SK_ABORT("Invalid GrColorType");
     return false;
@@ -110,11 +108,9 @@
         case kAlpha_half_as_Red_GrPixelConfig:  return false;
         case kGray_8_as_Lum_GrPixelConfig:      return false;
         case kGray_8_as_Red_GrPixelConfig:      return false;
+        // Experimental (for P016 and P010)
         case kR_16_GrPixelConfig:               return false;
         case kRG_1616_GrPixelConfig:            return false;
-        // Experimental (for Y416 and mutant P016/P010)
-        case kRGBA_16161616_GrPixelConfig:      return false;
-        case kRG_half_GrPixelConfig:            return false;
     }
     SK_ABORT("Invalid GrPixelConfig");
     return false;