drm/bridge: tc358762: Add basic driver for Toshiba TC358762 DSI-to-DPI bridge

Add very basic driver for Toshiba TC358762 DSI-to-DPI bridge, derived
from tc358764 driver and panel-raspberrypi-touchscreen. This driver is
meant to replace the panel-raspberrypi-touchscreen too, as the bridge
connection can be described in DT too.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: dri-devel@lists.freedesktop.org
Cc: Eric Anholt <eric@anholt.net>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: devicetree@vger.kernel.org
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam.ravnborg@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200809105705.6334-2-marex@denx.de