drm/amdgpu: refine the scheduler job type conversion

Use container_of rather than casting.

Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: David Zhou <david1.zhou@amd.com>
Signed-off-by: Junwei Zhang <Jerry.Zhang@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 58fe9fa..dbe061b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1277,6 +1277,8 @@
 	struct amdgpu_user_fence uf;
 	int (*free_job)(struct amdgpu_job *job);
 };
+#define to_amdgpu_job(sched_job)		\
+		container_of((sched_job), struct amdgpu_job, base)
 
 static inline u32 amdgpu_get_ib_value(struct amdgpu_cs_parser *p, uint32_t ib_idx, int idx)
 {