i5400_edac: improve debug messages to better represent the filled memory

Improves the debug output message, in order to better represent the
memory controller hierarchy, when outputing the debug messages.

No functional changes when debug is disabled.

Reviewed-by: Aristeu Rozanski <arozansk@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>