refactor(dt-bindings): align irq bindings with kernel

The arm-gic.h was a concatenation of arm-gic.h and irq.h from Linux.
Just copy the 2 files here. They both have MIT license which is accepted
in TF-A.
With this alignment, a new macro is added (GIC_CPU_MASK_SIMPLE).

Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Change-Id: Ib45174f35f1796ebb7f34af861b59810cfb808b0
diff --git a/include/dt-bindings/interrupt-controller/irq.h b/include/dt-bindings/interrupt-controller/irq.h
new file mode 100644
index 0000000..94e7f95
--- /dev/null
+++ b/include/dt-bindings/interrupt-controller/irq.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2021, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * This header provides constants for most IRQ bindings.
+ *
+ * Most IRQ bindings include a flags cell as part of the IRQ specifier.
+ * In most cases, the format of the flags cell uses the standard values
+ * defined in this header.
+ */
+
+#ifndef _DT_BINDINGS_INTERRUPT_CONTROLLER_IRQ_H
+#define _DT_BINDINGS_INTERRUPT_CONTROLLER_IRQ_H
+
+#define IRQ_TYPE_NONE		0
+#define IRQ_TYPE_EDGE_RISING	1
+#define IRQ_TYPE_EDGE_FALLING	2
+#define IRQ_TYPE_EDGE_BOTH	(IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING)
+#define IRQ_TYPE_LEVEL_HIGH	4
+#define IRQ_TYPE_LEVEL_LOW	8
+
+#endif