drm/i915/cnl: Add Cannonlake PCI IDs for U-skus.

Platform enabling and its power-on are organized in different
skus (U x Y x S x H, etc). So instead of organizing it in
GT1 x GT2 x GT3 let's also use the platform sku.

This is also the new Spec style what makes the review much
more easy and straightforward.

v2: Really include the PCI IDs to the picidlist[];
v3: Remove PCI IDs not present in spec.
v4: Rebase.

Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Clinton Taylor <clinton.a.taylor@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1496781040-20888-3-git-send-email-rodrigo.vivi@intel.com