dt-bindings: display/bridge: Add binding for NWL mipi dsi host controller

The Northwest Logic MIPI DSI IP core can be found in NXPs i.MX8 SoCs.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
Tested-by: Robert Chiras <robert.chiras@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/147ffc1e4dee3a623e5dca25d84565d386a34112.1586427783.git.agx@sigxcpu.org