dt-bindings: display: megachips-stdpxxxx-ge-b850v3-fw

Devicetree binding documentation for the second video output
of the GE B850v3:
   STDP4028-ge-b850v3-fw bridges (LVDS-DP)
   STDP2690-ge-b850v3-fw bridges (DP-DP++)

Added entry for MegaChips at:
 Documentation/devicetree/bindings/vendor-prefixes.txt

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Martyn Welch <martyn.welch@collabora.co.uk>
Cc: Martin Donnelly <martin.donnelly@ge.com>
Cc: Javier Martinez Canillas <javier@dowhile0.org>
Cc: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Senna Tschudin <peter.senna@collabora.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/c2712336226c5170cfdc45103527fb2338d3d6cf.1488555615.git.peter.senna@collabora.com