drm/i915: Copy PCI device id into the device info block

This is so that we can make the drm_i915_private->info always the
preferred source for chipset type and feature queries.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>