drm/i915/ddi: disable trancoder port select for 128b/132b SST

128b/1232b SST will have mst_master_transcoder set and matching
cpu_transcoder. Ensure disable also for 128b/132b SST.

Reviewed-by: Imre Deak <imre.deak@intel.com>
Co-developed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/eaf705b3490d828ba33e85f40a7794d58de7c5ad.1735912293.git.jani.nikula@intel.com