usb: core: constify the struct device_type usage

Since commit aed65af1 ("drivers: make device_type const"), the driver
core can properly handle constant struct device_type. Move the
usb_device_type, usb_if_device_type, usb_ep_device_type and
usb_port_device_type variables to be constant structures as well, placing
it into read-only memory which can not be modified at runtime.
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Link: https://lore.kernel.org/r/20240218-device_cleanup-usb-v1-4-77423c4da262@marliere.netSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/endpoint.c

@@ -141,7 +141,7 @@ static void ep_device_release(struct device *dev)
 	kfree(ep_dev);
 }
 
-struct device_type usb_ep_device_type = {
+const struct device_type usb_ep_device_type = {
 	.name =		"usb_endpoint",
 	.release = ep_device_release,
 };

drivers/usb/core/message.c

@@ -1849,7 +1849,7 @@ static int usb_if_uevent(const struct device *dev, struct kobj_uevent_env *env)
 	return 0;
 }
 
-struct device_type usb_if_device_type = {
+const struct device_type usb_if_device_type = {
 	.name =		"usb_interface",
 	.release =	usb_release_interface,
 	.uevent =	usb_if_uevent,

drivers/usb/core/port.c

@@ -429,7 +429,7 @@ static const struct dev_pm_ops usb_port_pm_ops = {
 #endif
 };
 
-struct device_type usb_port_device_type = {
+const struct device_type usb_port_device_type = {
 	.name =		"usb_port",
 	.release =	usb_port_device_release,
 	.pm =		&usb_port_pm_ops,

drivers/usb/core/usb.c

@@ -592,7 +592,7 @@ static char *usb_devnode(const struct device *dev,
 			 usb_dev->bus->busnum, usb_dev->devnum);
 }
 
-struct device_type usb_device_type = {
+const struct device_type usb_device_type = {
 	.name =		"usb_device",
 	.release =	usb_release_dev,
 	.uevent =	usb_dev_uevent,

drivers/usb/core/usb.h

@@ -144,10 +144,10 @@ static inline int usb_disable_usb2_hardware_lpm(struct usb_device *udev)
 extern const struct class usbmisc_class;
 extern const struct bus_type usb_bus_type;
 extern struct mutex usb_port_peer_mutex;
-extern struct device_type usb_device_type;
-extern struct device_type usb_if_device_type;
-extern struct device_type usb_ep_device_type;
-extern struct device_type usb_port_device_type;
+extern const struct device_type usb_device_type;
+extern const struct device_type usb_if_device_type;
+extern const struct device_type usb_ep_device_type;
+extern const struct device_type usb_port_device_type;
 extern struct usb_device_driver usb_generic_driver;
 
 static inline int is_usb_device(const struct device *dev)