drm/amdgpu: change pointer of mqd_ptr & mqd_backup to void

vi_mqd is only used by VI family but mqd_ptr and mqd_backup is
common for all ASIC, so change the pointer to void.

Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Monk Liu <Monk.Liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -783,7 +783,7 @@ struct amdgpu_mec {
 	u32 num_pipe;
 	u32 num_mec;
 	u32 num_queue;
-	struct vi_mqd	*mqd_backup[AMDGPU_MAX_COMPUTE_RINGS + 1];
+	void			*mqd_backup[AMDGPU_MAX_COMPUTE_RINGS + 1];
 };
 
 struct amdgpu_kiq {