drm/gma500: Make psb lvds use ddc adapter from drm_connector

We're moving all uses of ddc_bus to drm_connector where they belong.
Also cleanup the error handling in psb_intel_lvds_init() and remove
unused ddc_bus in psb_intel_lvds_priv.

Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220601092311.22648-6-patrik.r.jakobsson@gmail.com