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>

drivers/edac/sb_edac.c

@@ -2260,6 +2260,10 @@ static int sbridge_get_onedevice(struct pci_dev **prev,
 next_imc:
 	sbridge_dev = get_sbridge_dev(bus, dev_descr->dom, multi_bus, sbridge_dev);
 	if (!sbridge_dev) {
+
+		if (dev_descr->dom == SOCK)
+			goto out_imc;
+
 		sbridge_dev = alloc_sbridge_dev(bus, dev_descr->dom, table);
 		if (!sbridge_dev) {
 			pci_dev_put(pdev);
@@ -2285,6 +2289,7 @@ static int sbridge_get_onedevice(struct pci_dev **prev,
 	if (dev_descr->dom == SOCK && i < table->n_imcs_per_sock)
 		goto next_imc;
 
+out_imc:
 	/* Be sure that the device is enabled */
 	if (unlikely(pci_enable_device(pdev) < 0)) {
 		sbridge_printk(KERN_ERR,