drm/i915: If the GPU hangs twice within 5 seconds, declare it wedged.
The issue is that we may become stuck executing a long running shader and continually attempt to reset the GPU. (Or maybe we tickle some bug and need to break the vicious cycle.) So if we are detect a second hang within 5 seconds, give up trying to programme the GPU and report it wedged. Signed-off-by: Chris Wilson <email@example.com>