use SkImageInfo directly, instead of convert to Config

src/image/SkImage_Raster.cpp

Index: src/image/SkImage_Raster.cpp
diff --git a/src/image/SkImage_Raster.cpp b/src/image/SkImage_Raster.cpp
index 9863c337e0e5ef3cbbd53d40d2395ea477c39160..32d53fc52ec2b4cf7322e0fbd8790fe595cd959c 100644
--- a/src/image/SkImage_Raster.cpp
+++ b/src/image/SkImage_Raster.cpp
@@ -92,10 +92,9 @@ SkImage_Raster::SkImage_Raster(const Info& info, SkData* data, size_t rowBytes)
 }
 
 SkImage_Raster::SkImage_Raster(const Info& info, SkPixelRef* pr, size_t rowBytes)
-: INHERITED(info.fWidth, info.fHeight) {
-    SkBitmap::Config config = SkImageInfoToBitmapConfig(info);
-
-    fBitmap.setConfig(config, info.fWidth, info.fHeight, rowBytes, info.fAlphaType);
+    : INHERITED(info.fWidth, info.fHeight)
+{
+    fBitmap.setConfig(info, rowBytes);
     fBitmap.setPixelRef(pr);
 }