x86/amd_nb: Use topology info to get AMD node count

Currently, the total AMD node count is determined by searching and counting
CPU/node devices using PCI IDs.

However, AMD node information is already available through topology
CPUID/MSRs. The recent topology rework has made this info easier to access.

Replace the node counting code with a simple product of topology info.

Every node/northbridge is expected to have a 'misc' device. Clear everything
out if a 'misc' device isn't found on a node.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250107222847.3300430-7-yazen.ghannam@amd.com