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/platform.h b/plat/fvp/platform.h
index 01b995b..2024a9b 100644
--- a/plat/fvp/platform.h
+++ b/plat/fvp/platform.h
@@ -35,7 +35,7 @@
 #include <mmio.h>
 #include <psci.h>
 #include <bl_common.h>
-#include "io_storage.h"
+#include <io_storage.h>
 
 
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