tty: serdev: core: Fix misspelled function name __serdev_device_driver_register()

Fixes the following W=1 kernel build warning(s):

drivers/tty/serdev/core.c:809: warning: expecting prototype for serdev_driver_register(). Prototype was for __serdev_device_driver_register() instead

Cc: Rob Herring <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Jiri Slaby <[e-mail]>
Cc: [e-mail]
Signed-off-by: Lee Jones <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serdev/core.c

···
 EXPORT_SYMBOL_GPL(serdev_controller_remove);
 
 /**
- * serdev_driver_register() - Register client driver with serdev core
+ * __serdev_device_driver_register() - Register client driver with serdev core
  * @sdrv:	client driver to be associated with client-device.
  * @owner:	client driver owner to set.
  *