dt-bindings: altera: document VT compatibles

Add new compatible for SoCFPGA VT boards/designs.
Signed-off-by: NKrzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: NDinh Nguyen <dinguyen@kernel.org>

Documentation/devicetree/bindings/arm/altera.yaml

@@ -43,6 +43,11 @@ properties:
           - const: altr,socfpga-cyclone5
           - const: altr,socfpga
 
+      - description: SoCFPGA VT
+        items:
+          - const: altr,socfpga-vt
+          - const: altr,socfpga
+
 additionalProperties: true
 
 ...