Coverity: remove unnecessary header file includes

This patch removes unnecessary header file includes
discovered by Coverity HFA option.

Change-Id: I2827c37c1c24866c87db0e206e681900545925d4
Signed-off-by: Zelalem <zelalem.aweke@arm.com>
diff --git a/bl31/bl31_context_mgmt.c b/bl31/bl31_context_mgmt.c
index d41979f..9175ee3 100644
--- a/bl31/bl31_context_mgmt.c
+++ b/bl31/bl31_context_mgmt.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -11,7 +11,6 @@
 #include <context.h>
 #include <lib/el3_runtime/context_mgmt.h>
 #include <lib/el3_runtime/cpu_data.h>
-#include <plat/common/platform.h>
 
 /*******************************************************************************
  * This function returns a pointer to the most recent 'cpu_context' structure