stop using (deprecated) SkBitmap::Config

Change-Id: Ic75b5fc6996578e9d95bd3a220439ec1541d7c3b
diff --git a/libs/hwui/PathCache.cpp b/libs/hwui/PathCache.cpp
index 9dd5aa5..97eb583 100644
--- a/libs/hwui/PathCache.cpp
+++ b/libs/hwui/PathCache.cpp
@@ -104,8 +104,7 @@
 }
 
 static void initBitmap(SkBitmap& bitmap, uint32_t width, uint32_t height) {
-    bitmap.setConfig(SkBitmap::kA8_Config, width, height);
-    bitmap.allocPixels();
+    bitmap.allocPixels(SkImageInfo::MakeA8(width, height));
     bitmap.eraseColor(0);
 }