usb: ulpi: set mod_name in driver registration

The driver core only creates the sysfs "module" symlink for a built-in
driver when its struct device_driver has mod_name set (see
module_add_driver()). This driver left mod_name unset, so its built-in
form had no such symlink.

Set mod_name to KBUILD_MODNAME during driver registration. Built-in
drivers now gain the symlink, while loadable modules are unaffected.

Co-developed-by: Rahul Bukte <rahul.bukte@sony.com>
Signed-off-by: Rahul Bukte <rahul.bukte@sony.com>
Signed-off-by: Shashank Balaji <shashank.mahadasyam@sony.com>
Reviewed-by: Bastien Nocera <hadess@hadess.net>
Link: https://patch.msgid.link/20260722-mod_name_usb-v1-4-96d781530f3f@sony.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/common/ulpi.c

@@ -147,15 +147,17 @@ static const struct device_type ulpi_dev_type = {
  * __ulpi_register_driver - register a driver with the ULPI bus
  * @drv: driver being registered
  * @module: ends up being THIS_MODULE
+ * @mod_name: ends up being KBUILD_MODNAME
  *
  * Registers a driver with the ULPI bus.
  */
-int __ulpi_register_driver(struct ulpi_driver *drv, struct module *module)
+int __ulpi_register_driver(struct ulpi_driver *drv, struct module *module, const char *mod_name)
 {
 	if (!drv->probe)
 		return -EINVAL;
 
 	drv->driver.owner = module;
+	drv->driver.mod_name = mod_name;
 	drv->driver.bus = &ulpi_bus;
 
 	return driver_register(&drv->driver);

include/linux/ulpi/driver.h

@@ -51,8 +51,8 @@ struct ulpi_driver {
 /*
  * use a macro to avoid include chaining to get THIS_MODULE
  */
-#define ulpi_register_driver(drv) __ulpi_register_driver(drv, THIS_MODULE)
-int __ulpi_register_driver(struct ulpi_driver *drv, struct module *module);
+#define ulpi_register_driver(drv) __ulpi_register_driver(drv, THIS_MODULE, KBUILD_MODNAME)
+int __ulpi_register_driver(struct ulpi_driver *drv, struct module *module, const char *mod_name);
 void ulpi_unregister_driver(struct ulpi_driver *drv);
 
 #define module_ulpi_driver(__ulpi_driver) \