SW mask gen: release scratch bitmap after upload

This fixes a regression introduced in 366716, where we
were retaining the scratch bitmap. Before that change we were
destroying it after upload which is what we should do.

Bug: skia:11288
Change-Id: Ib567be037a2ff7595cd305a2ef3502d336795c46
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/367880
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Adlai Holler <adlai@google.com>
diff --git a/src/gpu/GrSWMaskHelper.cpp b/src/gpu/GrSWMaskHelper.cpp
index 69c254f..0914876 100644
--- a/src/gpu/GrSWMaskHelper.cpp
+++ b/src/gpu/GrSWMaskHelper.cpp
@@ -92,10 +92,7 @@
                                                        desc.fFit,
                                                        desc.fProtected,
                                                        mip);
-        GrProxyProvider::LazyCallbackResult result(std::move(tex));
-        // Callback refs us, we own bitmap, don't release callback.
-        result.fReleaseCallback = false;
-        return result;
+        return GrProxyProvider::LazyCallbackResult(std::move(tex));
     };
     const GrCaps* caps = context->priv().caps();
     GrProxyProvider* proxyProvider = context->priv().proxyProvider();