dt-bindings: display: bridge: lvds-transmitter: Document "ti, sn75lvds83"

Compatible string "ti,sn75lvds83" is being used by device tree
rk3188-bqedison2qc.dts, but it's not documented anywhere, therefore
document it within lvds-transmitter.yaml.
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1573660292-10629-5-git-send-email-fabrizio.castro@bp.renesas.com

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

@@ -37,6 +37,7 @@ properties:
       - enum:
         - ti,ds90c185       # For the TI DS90C185 FPD-Link Serializer
         - ti,ds90c187       # For the TI DS90C187 FPD-Link Serializer
+        - ti,sn75lvds83     # For the TI SN75LVDS83 FlatLink transmitter
       - const: lvds-encoder # Generic LVDS encoder compatible fallback
 
   ports: