drm/i915/dp_mst: Fix active port PLL selection for secondary MST streams

drm/i915/dp_mst: Fix active port PLL selection for secondary MST streams

The port PLL selection needs to be up-to-date in the CRTC state of both
the primary and all secondary MST streams. The commit removing the
encoder update_prepare/complete hooks (see Fixes: below), stopped doing
this for secondary streams, fix this up.

Fixes: 0f752b2178c9 ("drm/i915: Remove the encoder update_prepare()/complete() hooks")
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8336
Cc: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230414173800.590790-1-imre.deak@intel.com