PCI: create common pcibios_err_to_errno

For returning errors out to non-PCI code.  Re-name xen's version.

Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/xen/xen-pciback/conf_space.c

@@ -124,7 +124,7 @@ static inline u32 merge_value(u32 val, u32 new_val, u32 new_val_mask,
 	return val;
 }
 
-static int pcibios_err_to_errno(int err)
+static int xen_pcibios_err_to_errno(int err)
 {
 	switch (err) {
 	case PCIBIOS_SUCCESSFUL:
@@ -202,7 +202,7 @@ out:
 		       pci_name(dev), size, offset, value);
 
 	*ret_val = value;
-	return pcibios_err_to_errno(err);
+	return xen_pcibios_err_to_errno(err);
 }
 
 int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
@@ -290,7 +290,7 @@ int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
 		}
 	}
 
-	return pcibios_err_to_errno(err);
+	return xen_pcibios_err_to_errno(err);
 }
 
 void xen_pcibk_config_free_dyn_fields(struct pci_dev *dev)