drm: exynos: dsi: Convert to bridge driver

Some display panels would come up with a non-DSI output, those
can have an option to connect the DSI host by means of interface
bridge converter.

This DSI to non-DSI interface bridge converter would requires
DSI Host to handle drm bridge functionalities in order to DSI
Host to Interface bridge.

This patch convert the existing to a drm bridge driver with a
built-in encoder support for compatibility with existing
component drivers.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211122070633.89219-2-jagan@amarulasolutions.com