RDMA/srp: Remove the srp_host.released completion

Move the kfree(host) calls into srp_release_dev(). Convert a
device_unregister() call into a device_del() and a device_put() call.
Remove the host->released completion object. This patch prepares for
handling dev_set_name() failure in srp_add_port().

Link: https://lore.kernel.org/r/20220825213900.864587-3-bvanassche@acm.org


Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Leon Romanovsky <leon@kernel.org>