nvme-fabrics: remove superfluous nvmf_host_put in nvmf_parse_options

Opts->host is NULL there. It is checked just before. So remove
nvmf_host_put. It is introduced by commit 59a2f3f0

 ("nvme: fix
potential memory leak in option parsing").

Signed-off-by: Hou Pu <houpu.main@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>