Fix bufferpool

Fix bufferpool carsh sporadically on invalidation. use android::sp
instead of android::wp for caching IObserver hidl interface.

Bug: 112203066
Change-Id: I69aafa11cc617f9ae36cce88283a3294fcab9bbd
diff --git a/media/bufferpool/2.0/Accessor.h b/media/bufferpool/2.0/Accessor.h
index 4b5b17a..8d02519 100644
--- a/media/bufferpool/2.0/Accessor.h
+++ b/media/bufferpool/2.0/Accessor.h
@@ -185,6 +185,8 @@
      */
     static sp<ConnectionDeathRecipient> getConnectionDeathRecipient();
 
+    static void createInvalidator();
+
 private:
     class Impl;
     std::shared_ptr<Impl> mImpl;