nvme-fc: rename free_ctrl callback to match name pattern

Rename nvme_fc_nvme_ctrl_freed to nvme_fc_free_ctrl to match the name
pattern for the callback.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>