drm/i915/sdvo: Get rid of the per-connector i2c symlink

We should switch over to the standard "ddc" per-connector
symlink instead of rolling our own thing. The i2c specific
symlink is also in the way of reworking the SDVO DDC handling
(which is a mess atm) so get rid of it.

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/20230825134431.24391-5-ville.syrjala@linux.intel.com