dt-bindings: display: Add support for the BCM2711 HVS

The HVS found in the BCM2711 is slightly different from the previous
generations, let's add a compatible for it.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Hoegeun Kwon <hoegeun.kwon@samsung.com>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/a6b4c9ee03bc8f950adc6c493db70cd540c2f902.1599120059.git-series.maxime@cerno.tech

Documentation/devicetree/bindings/display/brcm,bcm2835-hvs.yaml

@@ -11,21 +11,37 @@ maintainers:
 
 properties:
   compatible:
-    const: brcm,bcm2835-hvs
+    enum:
+      - brcm,bcm2711-hvs
+      - brcm,bcm2835-hvs
 
   reg:
     maxItems: 1
 
   interrupts:
     maxItems: 1
 
+  clocks:
+    maxItems: 1
+    description: Core Clock
+
 required:
   - compatible
   - reg
   - interrupts
 
 additionalProperties: false
 
+if:
+  properties:
+    compatible:
+      contains:
+        const: brcm,bcm2711-hvs"
+
+then:
+  required:
+    - clocks
+
 examples:
   - |
     hvs@7e400000 {