drm/i915/ddi: pass encoder to intel_wait_ddi_buf_active()

Pass encoder to intel_wait_ddi_buf_active(). 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/6a299c4c575a260c0ba88b2e99931d48945269be.1710949619.git.jani.nikula@intel.com


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