[PATCH] drm/amdgpu: Fix build without CONFIG_HMM_MIRROR

[YueHaibing]

If CONFIG_HMM_MIRROR is not set, building may fails:

In file included from drivers/gpu/drm/amd/amdgpu/amdgpu.h:72:0,
                 from drivers/gpu/drm/amd/amdgpu/amdgpu_device.c:40:
drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h:69:20: error: field mirror has incomplete type
  struct hmm_mirror mirror;

Fixes: 7590f6d211ec ("drm/amdgpu: Prepare for hmm_range_register API change")
Signed-off-by: YueHaibing <yuehaibing at huawei.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h
index 281fd9f..b14f175 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.h
@@ -65,8 +65,10 @@ struct amdgpu_mn {
 	struct rw_semaphore	lock;
 	struct rb_root_cached	objects;
 
+#if defined(CONFIG_HMM_MIRROR)
 	/* HMM mirror */
 	struct hmm_mirror	mirror;
+#endif
 };
 
 #if defined(CONFIG_HMM_MIRROR)
-- 
2.7.4