Revert "drm/i915: fix infinite recursion on unbind due to ilk vt-d w/a"

This reverts commit eb1711b.

It blows up the i915 seqno tracking, resulting in the

	BUG_ON(seqno == 0);

in i915_wait_request() triggering, which will cause lock-ups.

See for example
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/903010
  https://lkml.org/lkml/2011/12/14/395

Reported-requested-and-tested-by: Dirk Hohndel <[email protected]>
Reported-by: Richard Eames <[email protected]>
Reported-by: Rocko Requin <[email protected]>
Acked-by: Daniel Vetter <[email protected]>
Cc: Dave Airlie <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Keith Packard <[email protected]>
Cc: Eric Anholt <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

drivers/gpu/drm/i915/i915_gem.c

@@ -2026,13 +2026,8 @@ i915_wait_request(struct intel_ring_buffer *ring,
 	 * to handle this, the waiter on a request often wants an associated
 	 * buffer to have made it to the inactive list, and we would need
 	 * a separate wait queue to handle that.
-	 *
-	 * To avoid a recursion with the ilk VT-d workaround (that calls
-	 * gpu_idle when unbinding objects with interruptible==false) don't
-	 * retire requests in that case (because it might call unbind if the
-	 * active list holds the last reference to the object).
 	 */
-	if (ret == 0 && dev_priv->mm.interruptible)
+	if (ret == 0)
 		i915_gem_retire_requests_ring(ring);
 
 	return ret;