PCI: Constify pci_dev_type structure

Make this const as it not modified in the file referencing it.  It is only
stored in a const field 'type' of a device structure.  Also, add const to
the variable declaration in the header file.
Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci-sysfs.c

@@ -1795,6 +1795,6 @@ static const struct attribute_group *pci_dev_attr_groups[] = {
 	NULL,
 };
 
-struct device_type pci_dev_type = {
+const struct device_type pci_dev_type = {
 	.groups = pci_dev_attr_groups,
 };

drivers/pci/pci.h

@@ -192,7 +192,7 @@ static inline int pci_no_d1d2(struct pci_dev *dev)
 }
 extern const struct attribute_group *pci_dev_groups[];
 extern const struct attribute_group *pcibus_groups[];
-extern struct device_type pci_dev_type;
+extern const struct device_type pci_dev_type;
 extern const struct attribute_group *pci_bus_groups[];