Make use of user/system includes more consistent

Make codebase consistent in its use of #include "" syntax for
user includes and #include <> syntax for system includes.

Fixes ARM-software/tf-issues#65

Change-Id: If2f7c4885173b1fd05ac2cde5f1c8a07000c7a33
diff --git a/plat/fvp/plat_security.c b/plat/fvp/plat_security.c
index a60eca3..042eb81 100644
--- a/plat/fvp/plat_security.c
+++ b/plat/fvp/plat_security.c
@@ -29,9 +29,9 @@
  */
 
 #include <assert.h>
-#include "platform.h"
-#include "tzc400.h"
-#include "debug.h"
+#include <platform.h>
+#include <tzc400.h>
+#include <debug.h>
 
 /* Used to improve readability for configuring regions. */
 #define FILTER_SHIFT(filter)	(1 << filter)