clean-up/simplify all dump() APIs

remove the scratch buffer parameter and use
String8::appendFormat() instead.

Change-Id: Ib96c91617c8e7292de87433d15cf6232b7d591b0
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.h b/services/surfaceflinger/DisplayHardware/HWComposer.h
index 604de38..a20da08 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.h
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.h
@@ -275,7 +275,7 @@
     friend class VSyncThread;
 
     // for debugging ----------------------------------------------------------
-    void dump(String8& out, char* scratch, size_t SIZE) const;
+    void dump(String8& out) const;
 
 private:
     void loadHwcModule();