drm/i915: Always stop the rings before a missing GPU reset

drm/i915: Always stop the rings before a missing GPU reset

Always try to stop the rings, even if the GPU reset itself has been
disabled (via modparam i915.reset). This should at least stop the hw
from spinning in the background consuming resources (e.g. power and
memory bandwidth) letting the system rest-in-peace.

References: https://bugs.freedesktop.org/show_bug.cgi?id=103260
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171013131218.18013-2-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>