make drivers with pci error handlers const

Covers the rest of the uses of pci error handler.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 097e536..0f1539e 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -871,7 +871,7 @@
 }
 
 /*add xen_pcibk AER handling*/
-static struct pci_error_handlers xen_pcibk_error_handler = {
+static const struct pci_error_handlers xen_pcibk_error_handler = {
 	.error_detected = xen_pcibk_error_detected,
 	.mmio_enabled = xen_pcibk_mmio_enabled,
 	.slot_reset = xen_pcibk_slot_reset,