dt-bindings: display: mediatek: split: Add compatible for MediaTek MT6795

Add a compatible string for MediaTek Helio X10 MT6795's SPLIT block: this
is the same as MT8173.

Signed-off-by: AngeloGioacchino Del Regno <[e-mail]>
Reviewed-by: Matthias Brugger <[e-mail]>
Acked-by: Krzysztof Kozlowski <[e-mail]>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/[e-mail]/
Signed-off-by: Chun-Kuang Hu <[e-mail]>

Documentation/devicetree/bindings/display/mediatek/mediatek,split.yaml

···
     oneOf:
       - enum:
           - mediatek,mt8173-disp-split
+      - items:
+          - const: mediatek,mt6795-disp-split
+          - const: mediatek,mt8173-disp-split
 
   reg:
     maxItems: 1