amd64_edac: Allocate driver instances dynamically

Remove static allocation in favor of dynamically allocating space for as
many driver instances as northbridges present on the system.

There should be no functional change resulting from this patch.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>

diff --cc drivers/edac/amd64_edac.c
Simple merge

diff --cc drivers/edac/amd64_edac.h
Simple merge