[natty] SRU: drm/i915: restore only the mode of this driver on lastclose (v2)

[Evan Broder]

https://bugs.launchpad.net/bugs/848687

SRU Justification:

Impact: When multiple DRI applications are running on an i965, and the
screen goes into standby, one of the applications will sometimes hang
when the screen is woken back up. Sometimes this occurs with compiz,
which renders the desktop unusable. In at least one case, the hang was
in DRI2GetBuffersWithFormat, though I don't know that that's
consistent.

Fix: Bisected e8e7a2b8ccfdae0d4cb6bd25824bbedcd42da316 as fix from
upstream kernel

Testcase: While using Unity, run "glxgears &" and "xset s 1". Continue
to wake up the screen when it goes into standby. On affected hardware,
either glxgears or compiz (i.e. the whole desktop) will eventually
hang

Patch is attached.

Thanks,
 - Evan
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