dt-bindings: display: bridge: fork out ti, ds90c185 from lvds-transmitter

DS90C185 has a shutdown pin which does not fit in the lvds-transmitter
binding, which is meant to be generic.

The sister chip DS90C187 is similar to DS90C185, describe it here as well.

Signed-off-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190111151843.11114-2-peda@axentia.se