modules: lvgl: fix initialization order depedencies

Removes the pseudo device prerequisite that the LVGL setup routine has been
executed before initialization. The pseudo devices are now registered at
the end of the LVGL setup routine, the driver is not concerned with
configuring the devices anymore. This also removes the need for enforcing
certain priorities within the same init level.

This resolves issue #62753.

Signed-off-by: Fabian Blatz <fabianblatz@gmail.com>