drm/amdgpu: Add nbif v6_3_1 ip block support

Add nbif v6_3_1 ip block support.

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Likun Gao <Likun.Gao@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>