nvmet-tcp: make nvmet_tcp_alloc_queue() a void function

The return value from nvmet_tcp_alloc_queue() are just used to
figure out if sock_release() need to be called. So this patch
moves sock_release() into nvmet_tcp_alloc_queue() and make it
a void function.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>