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/drivers/arm/gic/v2/gicv2_helpers.c b/drivers/arm/gic/v2/gicv2_helpers.c
index 6739a78..751316c 100644
--- a/drivers/arm/gic/v2/gicv2_helpers.c
+++ b/drivers/arm/gic/v2/gicv2_helpers.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -7,7 +7,6 @@
 #include <assert.h>
 
 #include <arch.h>
-#include <arch_helpers.h>
 #include <common/debug.h>
 #include <common/interrupt_props.h>
 #include <drivers/arm/gic_common.h>