drm/i915/dp: Move link train params to a substruct in intel_dp

drm/i915/dp: Move link train params to a substruct in intel_dp

For clarity move the link training parameters updated during link
training based on the pass/fail LT result under a substruct in intel_dp.
This prepares for later patches in this patchset adding similar params
here. Rename intel_dp_reset_max_link_params() to
intel_dp_reset_link_params() to better reflect what state gets reset.

v2: Add the parameters to a more generic link substruct. (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240610164933.2947366-3-imre.deak@intel.com