drm/amdgpu: split nbio callbacks into ras and non-ras ones

nbio ras is not managed by gpu driver when gpu is
connected to cpu through xgmi. split nbio callbacks
into ras and non-ras ones so gpu driver only
initializes nbio ras callbacks when it manages
nbio ras.

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Dennis Li <Dennis.Li@amd.com>
Reviewed-by: John Clements <John.Clements@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>