Use canonical UniquePtr.h header

Change-Id: Iab1dc428c2330a07a5944a1cfbb25c8134b11950
diff --git a/keystore-engine/eng_keystore.cpp b/keystore-engine/eng_keystore.cpp
index 6f5b01a..6feb0f9 100644
--- a/keystore-engine/eng_keystore.cpp
+++ b/keystore-engine/eng_keystore.cpp
@@ -23,7 +23,7 @@
  *
  */
 
-#include <utils/UniquePtr.h>
+#include <UniquePtr.h>
 
 #include <sys/socket.h>
 #include <stdarg.h>