drm/i915: Grab dev->struct_mutex in i915_gem_pageflip_info
drm/i915: Grab dev->struct_mutex in i915_gem_pageflip_info

We could walk of a bad list otherwise when someone concurrently
unbinds stuff for fun.

I've suspected this as the root-cause behind seemingly inconsistent
state, but alas it's not.

Acked-by: Chris Wilson <711c73f64afdce07b7e38039a96d2224209e9a6c@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs