Once device_add() failed, we should call only put_device() to
decrement reference count for cleanup. We should not call device_del()
before put_device().
As comment of device_add() says, 'if device_add() succeeds, you should
call device_del() when you want to get rid of it. If device_add() has
not succeeded, use only put_device() to drop the reference count'.
Found by code review.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: c8e4c2397655 ("RDMA/srp: Rework the srp_add_port() error path")
Signed-off-by: Ma Ke <make_ruc2021@xxxxxxx>