drivers/arm/css/scmi: Update power domain protocol version to 2.0

The SCMI power domain protocol in firmware has been updated to v2.0,
thus update the corresponding version in TF-A too.
Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
Change-Id: If3920ff71136dce94b2780e29a47f24aa09876c0

include/drivers/arm/css/scmi.h

 /*
- * Copyright (c) 2017-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -16,7 +16,7 @@
 
 /* Supported SCMI Protocol Versions */
 #define SCMI_AP_CORE_PROTO_VER			MAKE_SCMI_VERSION(1, 0)
-#define SCMI_PWR_DMN_PROTO_VER			MAKE_SCMI_VERSION(1, 0)
+#define SCMI_PWR_DMN_PROTO_VER			MAKE_SCMI_VERSION(2, 0)
 #define SCMI_SYS_PWR_PROTO_VER			MAKE_SCMI_VERSION(1, 0)
 
 #define GET_SCMI_MAJOR_VER(ver)			(((ver) >> 16) & 0xffff)