drm/i915: Nuke intel_dp_set_m_n()

I want to make a clean split betwen the CPU vs. PCH transcoder
programming. To that end eliminate intel_dp_set_m_n() and just
call the individual CPU/PCH transcoder functions directly.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220128103757.22461-2-ville.syrjala@linux.intel.com


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