drm/i915/opregion: unify intel_encoder/intel_connector naming

Prefer the short encoder/connector names for struct
intel_encoder/intel_connector variables and parameters.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/60c67da6b7282ab521366524109ade0470408cf8.1723213547.git.jani.nikula@intel.com


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