drm/i915: Use VMA as the primary tracker for semaphore page

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471254551-25805-23-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 259425d..50dc361 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -733,7 +733,7 @@
 	u64 fence[I915_MAX_NUM_FENCES];
 	struct intel_overlay_error_state *overlay;
 	struct intel_display_error_state *display;
-	struct drm_i915_error_object *semaphore_obj;
+	struct drm_i915_error_object *semaphore;
 
 	struct drm_i915_error_engine {
 		int engine_id;
@@ -1750,7 +1750,7 @@
 	struct pci_dev *bridge_dev;
 	struct i915_gem_context *kernel_context;
 	struct intel_engine_cs engine[I915_NUM_ENGINES];
-	struct drm_i915_gem_object *semaphore_obj;
+	struct i915_vma *semaphore;
 	u32 next_seqno;
 
 	struct drm_dma_handle *status_page_dmah;