dt-bindings: display: sunxi: Fix compatible

Commit f5a98bfe7b37 ("dt-bindings: display: Convert Allwinner display
pipeline to schemas") introduced a YAML schema for the Allwinner TCON DT
binding, but the H6 TCON-TV compatible was mistakenly set to fallback on
the A83t's, while the initial documentation and the DT are using R40's.

Fix that.

Fixes: f5a98bfe7b37 ("dt-bindings: display: Convert Allwinner display pipeline to schemas")
Signed-off-by: Maxime Ripard <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/devicetree/bindings/display/allwinner,sun4i-a10-tcon.yaml

···
         - enum:
           - allwinner,sun8i-h3-tcon-tv
           - allwinner,sun50i-a64-tcon-tv
-          - allwinner,sun50i-h6-tcon-tv
         - const: allwinner,sun8i-a83t-tcon-tv
+
+      - items:
+        - enum:
+          - allwinner,sun50i-h6-tcon-tv
+        - const: allwinner,sun8i-r40-tcon-tv
 
   reg:
     maxItems: 1