drm/i915/kbl: Change a KBL pci id to GT2 from GT1.5

See Mesa commit 9c588ff

Cc: Matt Turner <mattst88@gmail.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170920203126.1323-1-anuj.phogat@gmail.com