feat(drtm): add standard DRTM service

Added a dummy DRTM setup function and also, introduced DRTM SMCs
handling as per DRTM spec [1]. Few basic SMCs are handled in this
change such as ARM_DRTM_SVC_VERSION and ARM_DRTM_SVC_FEATURES
that returns DRTM version and functions ids supported respectively,
and others are dummy for now.

[1]: https://developer.arm.com/documentation/den0113/latest

Signed-off-by: Manish V Badarkhe <manish.badarkhe@arm.com>
Signed-off-by: Lucian Paul-Trifu <lucian.paultrifu@gmail.com>
Change-Id: I8c7afe920c78e064cbab2298f59e6837c70ba8ff
diff --git a/include/lib/smccc.h b/include/lib/smccc.h
index 1a39f24..9940ea9 100644
--- a/include/lib/smccc.h
+++ b/include/lib/smccc.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2021, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2022, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -41,6 +41,8 @@
 #define FUNCID_NUM_MASK			U(0xffff)
 #define FUNCID_NUM_WIDTH		U(16)
 
+#define FUNCID_MASK			U(0xffffffff)
+
 #define GET_SMC_NUM(id)			(((id) >> FUNCID_NUM_SHIFT) & \
 					 FUNCID_NUM_MASK)
 #define GET_SMC_TYPE(id)		(((id) >> FUNCID_TYPE_SHIFT) & \