dt-bindings: gpu: mali-midgard: Add H6 mali gpu compatible

This add the H6 mali compatible in the dt-bindings to later support
specific implementation.
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190521161102.29620-5-peron.clem@gmail.com

Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt

@@ -15,6 +15,7 @@ Required properties:
     + "arm,mali-t860"
     + "arm,mali-t880"
   * which must be preceded by one of the following vendor specifics:
+    + "allwinner,sun50i-h6-mali"
     + "amlogic,meson-gxm-mali"
     + "rockchip,rk3288-mali"
     + "rockchip,rk3399-mali"
@@ -52,9 +53,15 @@ Vendor-specific bindings
 ------------------------
 
 The Mali GPU is integrated very differently from one SoC to
-another. In order to accomodate those differences, you have the option
+another. In order to accommodate those differences, you have the option
 to specify one more vendor-specific compatible, among:
 
+- "allwinner,sun50i-h6-mali"
+  Required properties:
+  - clocks : phandles to core and bus clocks
+  - clock-names : must contain "core" and "bus"
+  - resets: phandle to GPU reset line
+
 - "amlogic,meson-gxm-mali"
   Required properties:
   - resets : Should contain phandles of :