Remove some uses of GrSurface::config()

Bug: skia:6718

Change-Id: I71ad95f910b6434e4d9a01c2750f1b2b08b2f6c4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/233567
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/src/gpu/GrTexture.cpp b/src/gpu/GrTexture.cpp
index c3dacaa..ec38c4f 100644
--- a/src/gpu/GrTexture.cpp
+++ b/src/gpu/GrTexture.cpp
@@ -79,7 +79,7 @@
 }
 
 void GrTexture::computeScratchKey(GrScratchKey* key) const {
-    if (!GrPixelConfigIsCompressed(this->config())) {
+    if (!this->getGpu()->caps()->isFormatCompressed(this->backendFormat())) {
         int sampleCount = 1;
         GrRenderable renderable = GrRenderable::kNo;
         if (const auto* rt = this->asRenderTarget()) {