drm/i915/mst: pass primary encoder to primary encoder hooks

drm/i915/mst: pass primary encoder to primary encoder hooks

Pass the primary encoder to the primary encoder hooks. This is
pedantically correct, but intel_ddi_post_pll_disable() also works with
the fake encoder by coincidence.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/a0151fddfdd5ec11a26345232cdd3ae59c8cf56a.1731409802.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>