config/udev: add pre_init stage to config and udev.
In order to use udev for gpu enumeration, we need to init udev earlier than input initialisations. This splits the config init stuff so that udev pre init sets up before output initialisation. this is just a prepatory patch, doesn't change anything major. Reviewed-by: Peter Hutterer <firstname.lastname@example.org> Signed-off-by: Dave Airlie <email@example.com>