drm/i915: use new macros to access the ring start register

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 2dfcd9b..9d0ae5a 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -9,6 +9,8 @@
 
 #define I915_READ_TAIL(ring) I915_READ(RING_TAIL(ring->mmio_base))
 #define I915_WRITE_TAIL(ring, val) I915_WRITE(RING_TAIL(ring->mmio_base), val)
+#define I915_READ_START(ring) I915_READ(RING_START(ring->mmio_base))
+#define I915_WRITE_START(ring, val) I915_WRITE(RING_START(ring->mmio_base), val)
 
 struct drm_i915_gem_execbuffer2;
 struct  intel_ring_buffer {
@@ -20,7 +22,6 @@
 	struct		ring_regs {
 			u32 ctl;
 			u32 head;
-			u32 start;
 	} regs;
 	u32		mmio_base;
 	unsigned long	size;