i915 register defines are going to become type safe, so going forward
the register defines can't be used as straight numbers. Since quirks.c
needs just a few extra register defines from i915_reg.h, decouple the
two by defining the required registers locally in quirks.c. This was
already done for a few other igpu related registers.

Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446672017-24497-2-git-send-email-ville.syrjala@linux.intel.comReviewed-by: Chris Wilson <chris@chris-wilson.co.uk>