drm/i915: Move PCH transcoder M/N setup into the PCH code

Do the PCH transcoder M/N setup next to where all the other
PCH transcoder stuff is programmed. Matches the spec modeset
sequence better.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220128103757.22461-8-ville.syrjala@linux.intel.com


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