drm/i915: Add i810/i815 pci-ids for completeness

To improve our historical record and to simplify userspace that wants to
include i915_pciids.h as its canonical breakdown of PCI IDs and their
respective generations, include the gen1 ids for i810 and i815.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170313112810.4202-1-chris@chris-wilson.co.uk


Acked-by: Jani Nikula <jani.nikula@intel.com>