video: ti: am335x: restore driver-model code

The commit 82f7b869 ("video: Drop CONFIG_AM335X_LCD") removed not
only the LCD legacy implementation but also the code with driver model
support. The patch restores the code with driver model support.

Fixes: 82f7b869 ("video: Drop CONFIG_AM335X_LCD")
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Simon Glass <sjg@chromium.org>