nvmet-fc: inline nvmet_fc_free_hostport

No need for this tiny helper with only one user, let's inline it.

And since the hostport ref counter needs to stay in sync, it's not
optional anymore to give back the reference.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>