Bug#914495: Bug appearing on Intel GM965

[sixerjman <sixerjman@gmail.com>]

I incorrectly stated there was no problem on one of my Debian machines with video adapter

Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (primary) (rev 0c).

There is black screen and lightdm failed to start after this:

BUG: unable to handle kernel NULL pointer dereference at 00000004

[Tue Dec  4 12:30:21 2018] *pdpt = 0000000036555001 *pde = 0000000000000000 

[Tue Dec  4 12:30:21 2018] Oops: 0000 [#1] SMP

[Tue Dec  4 12:30:21 2018] CPU: 0 PID: 316 Comm: systemd-udevd Not tainted 4.18.0-3-686-pae #1 Debian 4.18.20-2

[Tue Dec  4 12:30:21 2018] Hardware name: Dell Inc. Inspiron 1520                   /0KY767, BIOS A03 08/16/2007

[Tue Dec  4 12:30:21 2018] EIP: gen4_render_ring_flush+0x52/0x100 [i915]