drm/i915: Split some PCI ids into separate groups

This will enable the following patch to consolidate most device ids into
i915_pciids.h.

While cross-referencing the ids listed in i915_drv.h, with the ones listed
in i915_pciids.h, and also the comments in the latter, a bug for bug
approach was used. This means two things:

1.
Some ids are only present in i915_drv.h - obviously this means those parts
would not have been probed at all so they were not added to i915_pciids.h

2.
Some part type comments in i915_pciids.h were in disagreement with
i915_drv.h. For instance parts labeled as ULT or ULX were not considered
as such in i915_drv.h. The existing behaviour takes precedence here.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Suggested-by: Jani Nikula <jani.nikula@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190326074057.27833-4-tvrtko.ursulin@linux.intel.comReviewed-by: Chris Wilson <chris@chris-wilson.co.uk>