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/services/std_svc/psci/psci_entry.S b/services/std_svc/psci/psci_entry.S
index bdd571e..8a73e8b 100644
--- a/services/std_svc/psci/psci_entry.S
+++ b/services/std_svc/psci/psci_entry.S
@@ -31,10 +31,10 @@
 #include <arch.h>
 #include <platform.h>
 #include <psci.h>
-#include <psci_private.h>
 #include <runtime_svc.h>
 #include <asm_macros.S>
 #include <cm_macros.S>
+#include "psci_private.h"
 
 	.globl	psci_aff_on_finish_entry
 	.globl	psci_aff_suspend_finish_entry