clean-up/simplify all dump() APIs

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

Change-Id: Ib96c91617c8e7292de87433d15cf6232b7d591b0
diff --git a/services/surfaceflinger/DisplayDevice.h b/services/surfaceflinger/DisplayDevice.h
index 377d924..047eecd 100644
--- a/services/surfaceflinger/DisplayDevice.h
+++ b/services/surfaceflinger/DisplayDevice.h
@@ -153,7 +153,7 @@
      * Debugging
      */
     uint32_t getPageFlipCount() const;
-    void dump(String8& result, char* buffer, size_t SIZE) const;
+    void dump(String8& result) const;
 
 private:
     /*