It's completely pointless to have two pointers to the
device in the same structure.

v2: rename function to amdgpu_ttm_adev, fix typos
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>