overlay: rotator: Remove previous allocation for a session

When ION was not ref counted, we needed to maintain the previous
session memory until the new one was taken by MDP. ION being
ref counted now, it is not necessary to maintain previous memory
allocation.

Change-Id: I102df065bb288a661d509912f4c7b894505df393
diff --git a/liboverlay/overlayUtils.h b/liboverlay/overlayUtils.h
index 24fba33..959dadf 100644
--- a/liboverlay/overlayUtils.h
+++ b/liboverlay/overlayUtils.h
@@ -424,7 +424,7 @@
 const char* getFormatString(int format);
 
 template <class T>
-inline void memset0(T& t) { ::memset(&t, 0, sizeof(T)); }
+inline void memset0(T& t) { ::memset(&t, 0, sizeof(t)); }
 
 template <class T> inline void swap ( T& a, T& b )
 {