drm/i915: fix the "ghost eDP" connector unwind path

Because calling intel_dp_destroy inside intel_edp_init_connector is
just wrong. This is the initialization path, so we should properly
unwind all the initialization through the whole caller stack.

On the intel_dp_destroy function we do the following:
1 - Free edid if it exists
2 - Call intel_panel_fini in case it's eDP
3 - Call drm_sysfs_connector_remove
4 - Call drm_connector_cleanup
5 - Free the connector

And here is how we unwind each specific step:
1 - No need as we still didn't assign anything
2 - No need as we still didn't call intel_panel_init
3 - Call it in the same function that called drm_sysfs_connector_add
4 - Call it in the same function that called drm_connector_init
5 - Free it in the same function that allocated it

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Zoltan Nyul <zoltan.nyul@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>