drm/i915: eliminate dead domain clearing on reset

The code itself is no longer accurate without updating once we have
multiple address space since clearing the domains of every object
requires scanning the inactive list for all VMs.

"This code is dead. Just remove it rather than port it to vma." - Chris
Wilson

Recommended-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ben Widawsky <benjamin.widawsky@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -2291,20 +2291,12 @@ void i915_gem_restore_fences(struct drm_device *dev)
 void i915_gem_reset(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct i915_address_space *vm = &dev_priv->gtt.base;
-	struct drm_i915_gem_object *obj;
 	struct intel_ring_buffer *ring;
 	int i;
 
 	for_each_ring(ring, dev_priv, i)
 		i915_gem_reset_ring_lists(dev_priv, ring);
 
-	/* Move everything out of the GPU domains to ensure we do any
-	 * necessary invalidation upon reuse.
-	 */
-	list_for_each_entry(obj, &vm->inactive_list, mm_list)
-		obj->base.read_domains &= ~I915_GEM_GPU_DOMAINS;
-
 	i915_gem_restore_fences(dev);
 }