drm/i915: kill ring->get_active_head

All functions are extremely similar, so fold them into one generic
implementation.

This function isn't used anyway, because there's not yet a bsd ring
error state dumper.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index d506da1..43c5f7a 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -50,8 +50,6 @@
 	void		(*set_tail)(struct drm_device *dev,
 				    struct intel_ring_buffer *ring,
 				    u32 value);
-	unsigned int	(*get_active_head)(struct drm_device *dev,
-			struct intel_ring_buffer *ring);
 	void		(*flush)(struct drm_device *dev,
 			struct intel_ring_buffer *ring,
 			u32	invalidate_domains,
@@ -128,4 +126,7 @@
 int intel_init_render_ring_buffer(struct drm_device *dev);
 int intel_init_bsd_ring_buffer(struct drm_device *dev);
 
+u32 intel_ring_get_active_head(struct drm_device *dev,
+			       struct intel_ring_buffer *ring);
+
 #endif /* _INTEL_RINGBUFFER_H_ */