drm/gma500: Make cdv hdmi use ddc adapter from drm_connector

We're moving all uses of ddc_bus from gma_encoder to drm_connector where
they belong. Also, cleanup the error handling in cdv_hdmi_init()
and remove unused i2c pointer in mid_intel_hdmi_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/20220601092311.22648-5-patrik.r.jakobsson@gmail.com