drm/amdgpu: change r type to int in gmc_v9_0_late_init

change r type from bool to int, suitable for both bool and int return
value

Signed-off-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>