Add Skylake Intel Graphics GT4 PCI IDs

v2: Rebase
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446811876-303-1-git-send-email-mika.kuoppala@intel.com