dt-bindings: display: bridge: lvds-transmitter: Absorb ti, ds90c185.txt

ti,ds90c185.txt documents LVDS encoders using the same driver
as the one documented by lvds-transmitter.yaml.
Since the properties listed in ti,ds90c185.txt are the same
as the ones listed in lvds-transmitter.yaml, absorb the dt-binding
into lvds-transmitter.yaml.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-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/1573660292-10629-4-git-send-email-fabrizio.castro@bp.renesas.com