drm/i915: Refactor EDID fixed mode search

Both LVDS and eDP have the same code to look up the preferred mode
from the connector probed_modes list. Move the code to a common
location.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190321132446.22394-1-ville.syrjala@linux.intel.com


Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Jani Nikula <jani.nikula@intel.com>