drm/i915: use lane count and link rate from VBT as minimums for eDP

drm/i915: use lane count and link rate from VBT as minimums for eDP

Most likely the minimums for both should be enough for enabling the
native resolution on the eDP, and we'll end up using the predetermined
optimal link config for the panel.

v2: Add debug prints.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73539
Tested-by: Markus Blank-Burian <burian@muenster.de>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>