dt-bindings: Add a new binding for Broadcom V3D 3.x and newer GPUs.

These OpenGL ES GPUs are present in the 7268 and 7278 set top box
chips.

v2: no changes
v3: move to gpu/, fix typo
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180430181058.30181-2-eric@anholt.netReviewed-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/gpu/brcm,bcm-v3d.txt

+Broadcom V3D GPU
+
+Only the Broadcom V3D 3.x and newer GPUs are covered by this binding.
+For V3D 2.x, see brcm,bcm-vc4.txt.
+
+Required properties:
+- compatible:	Should be "brcm,7268-v3d" or "brcm,7278-v3d"
+- reg:		Physical base addresses and lengths of the register areas
+- reg-names:	Names for the register areas.  The "hub", "bridge", and "core0"
+		  register areas are always required.  The "gca" register area
+		  is required if the GCA cache controller is present.
+- interrupts:	The interrupt numbers.  The first interrupt is for the hub,
+		  while the following interrupts are for the cores.
+		  See bindings/interrupt-controller/interrupts.txt
+
+Optional properties:
+- clocks:	The core clock the unit runs on
+
+v3d {
+	compatible = "brcm,7268-v3d";
+	reg = <0xf1204000 0x100>,
+	      <0xf1200000 0x4000>,
+	      <0xf1208000 0x4000>,
+	      <0xf1204100 0x100>;
+	reg-names = "bridge", "hub", "core0", "gca";
+	interrupts = <0 78 4>,
+		     <0 77 4>;
+};