sb_edac: Degrade log level for device registration

On a system with four Intel processors, it generates too many messages
"EDAC sbridge: Seeking for: dev 1d.3 PCI ID xxxx". And it doesn't give
many useful information for normal users, so change log level from INFO
to DEBUG.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Link: http://lkml.kernel.org/r/1392613824-11230-1-git-send-email-jiang.liu@linux.intel.com
Acked-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>