remove prepForSampling from GrSurfaceContext::writePixels.

We believe with advent of  GrBackendSurfaceMutableState that this is
only needed for inline atlas uploads. Those call GrGpu directly.

Bug: 1191058
Change-Id: Iad851ebc9f5b7df21d16064a84caa9575da98634
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/393082
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/GrDirectContext.cpp b/src/gpu/GrDirectContext.cpp
index cbd9d3b..69f60c5 100644
--- a/src/gpu/GrDirectContext.cpp
+++ b/src/gpu/GrDirectContext.cpp
@@ -527,7 +527,7 @@
     for (int i = 0; i < numLevels; ++i) {
         tmpSrc[i] = src[i];
     }
-    if (!surfaceContext.writePixels(context, tmpSrc.get(), numLevels, /*prep for sampling*/ true)) {
+    if (!surfaceContext.writePixels(context, tmpSrc.get(), numLevels)) {
         return false;
     }