arm64: dts: mba8mx: Add DSI-LVDS bridge nodes

This adds the DSI-LVDS bridge including the regulator, backlight and
an unspecified panel. It is expected to set the compatible when the
display chain is enabled.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>