[PATCH v2] drm/i915: refine qemu south bridge detection

[Bruno Wolff III]

On Mon, Jan 25, 2016 at 12:02:28 +0100,
  Gerd Hoffmann <kraxel at redhat.com> wrote:
>
>Refine the check by additionally verifying the pci
>subsystem id to see whenever it *really* is qemu.
>
>[ v2: fix subvendor tyops ]

I tested this patch on my laptop that was getting a black screen part way 
through the boot process and it fixed things.