drm/i915: Stop duplicating the EDID fixed/downclock modes

drm/i915: Stop duplicating the EDID fixed/downclock modes

Instead of duplicating the fixed/downclock modes we can just grab
the originals straight from the probed_modes list and keep them.
The next .get_modes() is going to repopulate the probed_modes list
anyway so whatever we leave there is just going to sit around until
that time wasting memory. In fact let's clear out the probed modes
list entirely to make sure we get 100% consistent behaviour starting
already from the very first real .get_modes().

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220331112822.11462-7-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>