drm/i915/skl: port A fuse straps don't work on early SKL steppings

So try to enumerate eDP unconditionally in those cases.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
[danvet: Add wa tag Damien dug out.]
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>