In preparation to track per ring progress in hangcheck,
add i915_hangcheck_ring_hung.
v2: omit dev parameter (Ben Widawsky)
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com> Reviewed-by: Ben Widawsky <ben@bwidawsk.net> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>