Use the helper function in TTM to get TTM mem limit and
set GTT size to be equal to TTL mem limit.
Signed-off-by: Mukul Joshi <mukul.joshi@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>