drm/meson: add DSI encoder

This adds an encoder bridge designed to drive a MIPI-DSI display
by using the ENCL encoder through the internal MIPI DSI transceiver
connected to the output of the ENCL pixel encoder.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Nicolas Belin <nbelin@baylibre.com>
Tested-by: Nicolas Belin <nbelin@baylibre.com> # on Khadas VIM3 + TS050 Panel
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230512-amlogic-v6-4-upstream-dsi-ccf-vim3-v5-11-56eb7a4d5b8e@linaro.org