drm/i915: Refactor i915_gem_retire_requests()

Combine the iteration over active render rings into a common function.
This is in preparation for reusing the idle function to also retire
deferred free requests.

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_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 46a544a..a27780b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -960,8 +960,7 @@
 bool i915_seqno_passed(uint32_t seq1, uint32_t seq2);
 int i915_gem_object_get_fence_reg(struct drm_gem_object *obj);
 int i915_gem_object_put_fence_reg(struct drm_gem_object *obj);
-void i915_gem_retire_requests(struct drm_device *dev,
-		 struct intel_ring_buffer *ring);
+void i915_gem_retire_requests(struct drm_device *dev);
 void i915_gem_retire_work_handler(struct work_struct *work);
 void i915_gem_clflush_object(struct drm_gem_object *obj);
 int i915_gem_object_set_domain(struct drm_gem_object *obj,