drm/i915: fix hibernation since i915 self-reclaim fixes

Since commit 4bdadb97 ("drm/i915:
Selectively enable self-reclaim"), we've been passing GFP_MOVABLE to the
i915 page allocator where we weren't before due to some over-eager
removal of the page mapping gfp_flags games the code used to play.

This caused hibernate on Intel hardware to result in a lot of memory
corruptions on resume.  See for example

  http://bugzilla.kernel.org/show_bug.cgi?id=13811



Reported-by: Evengi Golov (in bugzilla)
Signed-off-by: Dave Airlie <airlied@redhat.com>
Tested-by: M. Vefa Bicakci <bicave@superonline.com>
Cc: stable@kernel.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>