PCI: Change pci_host_common_probe() visibility

pci_host_common_probe() is defined when CONFIG_PCI_HOST_COMMON=y;
therefore the function declaration should match that.

  drivers/pci/host/pcie-tango.c:300:9: error:
	implicit declaration of function 'pci_host_common_probe'

Signed-off-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

include/linux/pci-ecam.h

@@ -69,7 +69,7 @@ extern struct pci_ecam_ops xgene_v1_pcie_ecam_ops; /* APM X-Gene PCIe v1 */
 extern struct pci_ecam_ops xgene_v2_pcie_ecam_ops; /* APM X-Gene PCIe v2.x */
 #endif
 
-#ifdef CONFIG_PCI_HOST_GENERIC
+#ifdef CONFIG_PCI_HOST_COMMON
 /* for DT-based PCI controllers that support ECAM */
 int pci_host_common_probe(struct platform_device *pdev,
 			  struct pci_ecam_ops *ops);