intel: Add Cannonlake PCI IDs for Y-skus.

By the Spec all CNL Y skus are 2+2, i.e. GT2.

This is a copy of merged i915's
commit 95578277cbdb ("drm/i915/cnl: Add Cannonlake PCI IDs for Y-skus.")

v2: 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>