drm/i2c: adv7511: Create mipi_dsi_device for ADV7533

In order to pass DSI specific parameters to the DSI host, we need the
driver to create a mipi_dsi_device DSI device that attaches to the
host.

Use of_graph helpers to get the DSI host DT node. Create a MIPI DSI
device using this host. Finally, attach this device to the DSI host.

Populate DT parameters (number of data lanes for now) that are required
for DSI RX to work correctly. Hardcode few other parameters (rgb,
embedded_sync) for now.

Signed-off-by: Archit Taneja <architt@codeaurora.org>