drm/i915: include hangcheck action and score in error_state

Score and action reveals what all the rings were doing
and why hang was declared. Add idle state so that
we can distinguish between waiting and idle ring.

v2: - add idle as a hangcheck action
    - consensed hangcheck status to single line (Chris)
    - mark active explicitly when we are making progress (Chris)

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>