x86: Fix CPU llc_shared_map information for AMD Magny-Cours

Construct entire NodeID and use it as cpu_llc_id. Thus internal node
siblings are stored in llc_shared_map.

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>