drm/i915: Include GT/seqno activity in engine/hangcheck debugfs

drm/i915: Include GT/seqno activity in engine/hangcheck debugfs

Whilst investigating some mysterious failures with hangcheck not running
during gem_busy/basic-hang-default, the question is why did we decide to
cancel the retire_work (which queues the hangcheck)? That decision is
based around GT activity, so include that information in the debug
report.

v2: Include the GT awake status in the error state

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170302150356.9713-1-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>