test(el3-runtime): dit is retained on world switch

Add tsp service to check the value of the PSTATE DIT bit is as
expected and toggle it's value. This is used to ensure that
the DIT bit is maintained during a switch from the Normal to
Secure worlds and back.

Change-Id: I4e8bdfa6530e5e75925c0079d4fa2795133c5105
Signed-off-by: Daniel Boulby <daniel.boulby@arm.com>
diff --git a/include/bl32/tsp/tsp.h b/include/bl32/tsp/tsp.h
index 637e14a..285bfbe 100644
--- a/include/bl32/tsp/tsp.h
+++ b/include/bl32/tsp/tsp.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2022, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -41,6 +41,7 @@
 #define TSP_MUL		0x2002
 #define TSP_DIV		0x2003
 #define TSP_HANDLE_SEL1_INTR_AND_RETURN	0x2004
+#define TSP_CHECK_DIT	0x2005
 
 /*
  * Identify a TSP service from function ID filtering the last 16 bits from the