drm/i915: Don't add panel_fixed_mode to the probed modes list at LVDS init.

In the case where no EDID data is read from the device, adding the
panel_fixed_mode pointer to the probed modes list causes data corruption.

If the panel_fixed_mode pointer is added to the probed modes list at
init time, a copy of the mode is added again at drm_get_modes() request
time.  Then, the panel_fixed_mode pointer is freed because it is seen as
a duplicate mode.  Unfortunately, this pointer is still stored and used
in mode_fixup().

Because the panel_fixed_mode data is copied and returned at
drm_get_modes() time, it is unnecessary to add this information at init
time.

Signed-off-by: Steve Aarnio <steve.j.aarnio@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@linux.ie>