dt-bindings: display: bridge: lvds-codec: Document pixel data sampling edge select

The OnSemi FIN3385 Parallel-to-LVDS encoder has a dedicated input line to
select input pixel data sampling edge. Add DT property "pclk-sample", not
the same as the one used by display timings but rather the same as used by
media, to define the pixel data sampling edge.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: devicetree@vger.kernel.org
To: dri-devel@lists.freedesktop.org
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20211017001204.299940-1-marex@denx.de

Documentation/devicetree/bindings/display/bridge/lvds-codec.yaml

@@ -79,6 +79,14 @@ properties:
       - port@0
       - port@1
 
+  pclk-sample:
+    description:
+      Data sampling on rising or falling edge.
+    enum:
+      - 0  # Falling edge
+      - 1  # Rising edge
+    default: 0
+
   powerdown-gpios:
     description:
       The GPIO used to control the power down line of this device.
@@ -102,6 +110,16 @@ then:
               properties:
                 data-mapping: false
 
+if:
+  not:
+    properties:
+      compatible:
+        contains:
+          const: lvds-encoder
+then:
+  properties:
+    pclk-sample: false
+
 required:
   - compatible
   - ports