drm/i915: Always call i915_gem_reset_finish() following i915_gem_reset_prepare()

As i915_gem_reset_finish() undoes the steps from
i915_gem_reset_prepare() to leave the system in a fully-working state,
e.g. to be able to free the breadcrumb signal threads, make sure that we
always call it even on the error path.

Fixes: da9a796f54 ("drm/i915: Split GEM resetting into 3 phases")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170212172002.23072-2-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
(cherry picked from commit 8d613c539c)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_drv.c

@@ -1809,10 +1809,10 @@ void i915_reset(struct drm_i915_private *dev_priv)
 		goto error;
 	}
 
-	i915_gem_reset_finish(dev_priv);
 	i915_queue_hangcheck(dev_priv);
 
 wakeup:
+	i915_gem_reset_finish(dev_priv);
 	enable_irq(dev_priv->drm.irq);
 	wake_up_bit(&error->flags, I915_RESET_IN_PROGRESS);
 	return;