drm/i915: Call the DDC bus i2c adapter "ddc"

Rename the various names we've used for the DDC bus
i2c adapter ("i2c", "adapter", etc.) to just "ddc".
This differentiates it from the various other i2c
busses we might have (DSI panel stuff, DVO control bus, etc.).

v2: Don't add a bogus drm_get_edid() call (Jani)

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230831104300.29688-1-ville.syrjala@linux.intel.com