drm/i915: Use a common seqno for all rings.

This will be used by the eviction logic to maintain fairness between the
rings.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index f150bfd..45b9982 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4714,6 +4714,8 @@
 			goto cleanup_render_ring;
 	}
 
+	dev_priv->next_seqno = 1;
+
 	return 0;
 
 cleanup_render_ring: