powerpc/pseries: fix possible memory leak in ibmebus_bus_init()

In the Linux kernel, the following vulnerability has been resolved:

powerpc/pseries: fix possible memory leak in ibmebus_bus_init()

If device_register() returns error in ibmebus_bus_init(), name of kobject

which is allocated in dev_set_name() called in device_add() is leaked.

As comment of device_add() says, it should call put_device() to drop

the reference count that was set in device_initialize() when it fails,

so the name can be freed in kobject_cleanup().