Move TSP private declarations into separate header

Move the TSP private declarations out of tsp.h and into a new
header, tsp_private.h. This clarifies the TSP interface to the TSPD.

Change-Id: I39af346eeba3350cadcac56c02d97a5cb978c28b
diff --git a/bl32/tsp/tsp_main.c b/bl32/tsp/tsp_main.c
index 982bab2..31808fc 100644
--- a/bl32/tsp/tsp_main.c
+++ b/bl32/tsp/tsp_main.c
@@ -35,6 +35,7 @@
 #include <platform_def.h>
 #include <spinlock.h>
 #include <tsp.h>
+#include "tsp_private.h"
 
 /*******************************************************************************
  * Declarations of linker defined symbols which will help us find the layout