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.

This is a copy of merged i915's
commit e918d79a5d0a ("drm/i915/cnl: Add Cannonlake PCI IDs for U-skus.")

v2: Based on Anusha's kernel clean-up.
v3: Add kernel commit id for reference.

Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Clinton Taylor <clinton.a.taylor@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Clinton Taylor <clinton.a.taylor@intel.com>