driver core: bus: constantify bus_register()

bus_register() is now safe to take a constant * to bus_type, so make
that change and mark the subsys_private bus_type * constant as well.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230313182918.1312597-24-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/base.h

@@ -49,7 +49,7 @@ struct subsys_private {
 	struct klist klist_drivers;
 	struct blocking_notifier_head bus_notifier;
 	unsigned int drivers_autoprobe:1;
-	struct bus_type *bus;
+	const struct bus_type *bus;
 	struct device *dev_root;
 
 	struct kset glue_dirs;

drivers/base/bus.c

@@ -841,7 +841,7 @@ static struct bus_attribute bus_attr_uevent = __ATTR(uevent, 0200, NULL,
  * infrastructure, then register the children subsystems it has:
  * the devices and drivers that belong to the subsystem.
  */
-int bus_register(struct bus_type *bus)
+int bus_register(const struct bus_type *bus)
 {
 	int retval;
 	struct subsys_private *priv;

include/linux/device/bus.h

@@ -110,7 +110,7 @@ struct bus_type {
 	bool need_parent_lock;
 };
 
-extern int __must_check bus_register(struct bus_type *bus);
+extern int __must_check bus_register(const struct bus_type *bus);
 
 extern void bus_unregister(const struct bus_type *bus);