GIC: Fix setting interrupt configuration

  - Interrupt configuration is a 2-bit field, so the field shift has to
    be double that of the bit number.

  - Interrupt configuration (level- or edge-trigger) is specified in the
    MSB of the field, not LSB.

Fixes applied to both GICv2 and GICv3 drivers.

Fixes ARM-software/tf-issues#570

Change-Id: Ia6ae6ed9ba9fb0e3eb0f921a833af48e365ba359
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/include/drivers/arm/gic_common.h b/include/drivers/arm/gic_common.h
index 001f573..6e953a0 100644
--- a/include/drivers/arm/gic_common.h
+++ b/include/drivers/arm/gic_common.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -29,9 +29,9 @@
 /* Constant to indicate a spurious interrupt in all GIC versions */
 #define GIC_SPURIOUS_INTERRUPT		1023
 
-/* Interrupt configurations */
-#define GIC_INTR_CFG_LEVEL		0
-#define GIC_INTR_CFG_EDGE		1
+/* Interrupt configurations: 2-bit fields with LSB reserved */
+#define GIC_INTR_CFG_LEVEL		(0 << 1)
+#define GIC_INTR_CFG_EDGE		(1 << 1)
 
 /* Constants to categorise priorities */
 #define GIC_HIGHEST_SEC_PRIORITY	0x0