While the current amdgpu doesn't support TMZ, it will return the error if user
mode would like to allocate secure buffer.

v2: we didn't need this checking anymore.
v3: only print message once time.
Signed-off-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Nirmoy Das <Nirmoy.Das@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>