EDAC, sb_edac: Avoid creating SOCK memory controller

Xiaolong Ye reported the following failure on Broadwell D server:

  EDAC sbridge: Some needed devices are missing
  EDAC MC: Removed device 0 for sbridge_edac.c Broadwell SrcID#0_Ha#0: DEV 0000:ff:12.0
  EDAC sbridge: Couldn't find mci handler
  EDAC sbridge: Failed to register device with error -19.

Broadwell D (only IMC0 per socket) and Broadwell X (IMC0 and IMC1 per
socket) use the same PCI device IDs for IMC0 per socket, then they
share pci_dev_descr_broadwell_table (n_imcs_per_sock=2). In this case,
Broadwell D wrongly creates the nonexistent SOCK EDAC memory controller
and reports above error messages, since it has no IMC1 per socket.

Avoid creating the nonexistent SOCK memory controller.

Reported-and-tested-by: Xiaolong Ye <xiaolong.ye@intel.com>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: http://lkml.kernel.org/r/20170608113351.25323-1-qiuxu.zhuo@intel.com


[ Massage. ]
Signed-off-by: Borislav Petkov <bp@suse.de>