dt-bindings: add binding for the Allwinner DE2 CCU

Allwinner "Display Engine 2.0" contains some clock controls in it.

In order to add them as clock drivers, we need a device tree binding.
Add the binding here.

Also add the device tree binding headers.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

include/dt-bindings/clock/sun8i-de2.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (C) 2016 Icenowy Zheng <icenowy@aosc.io>
+ *
+ * SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+ */
+
+#ifndef _DT_BINDINGS_CLOCK_SUN8I_DE2_H_
+#define _DT_BINDINGS_CLOCK_SUN8I_DE2_H_
+
+#define CLK_BUS_MIXER0		0
+#define CLK_BUS_MIXER1		1
+#define CLK_BUS_WB		2
+
+#define CLK_MIXER0		6
+#define CLK_MIXER1		7
+#define CLK_WB			8
+
+#endif /* _DT_BINDINGS_CLOCK_SUN8I_DE2_H_ */