PNP: constify driver name

struct pnp_driver has name set as char* instead of const char* like platform_driver, pci_driver, usb_driver, etc...
Let's unify a bit by setting name as const char*.
Furthermore, all users of this structures set name from already const
data.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/linux/pnp.h

@@ -379,7 +379,7 @@ struct pnp_id {
 };
 
 struct pnp_driver {
-	char *name;
+	const char *name;
 	const struct pnp_device_id *id_table;
 	unsigned int flags;
 	int (*probe) (struct pnp_dev *dev, const struct pnp_device_id *dev_id);