drm/i915: Differentiate between hangcheck waiting for timer or scheduler

drm/i915: Differentiate between hangcheck waiting for timer or scheduler

Check timer_pending() as well as work_pending() to see if the timer for
the hangcheck has already expired and the work is pending execution on
some list somewhere.

v2: Use a more compact if-chain

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/20170303090056.19973-1-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>