drm/i915/gt: Call stop_ring() from ring resume, again

drm/i915/gt: Call stop_ring() from ring resume, again

For reasons I cannot explain, except to say this is Sandybridge after
all, call stop_ring() again dring ring resume in order to prevent
mysterious hard hangs.

Testcase: igt/i915_selftest/hangcheck # snb
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Acked-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210121154950.19898-3-chris@chris-wilson.co.uk
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>