drm/i915/hdmi: convert *_port_to_ddc_pin() to *_encoder_to_ddc_pin()

Pass encoder to the _port_to_ddc_pin() functions, and rename to
_encoder_to_ddc_pin(). The encoder will be more helpful than just port
in the subsequent changes.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c94debf36816157de1105a186b061fd90dab574a.1710949619.git.jani.nikula@intel.com


Signed-off-by: Jani Nikula <jani.nikula@intel.com>