nvme-fabrics: use kfree_sensitive() for DHCHAP secrets

nvme-fabrics: use kfree_sensitive() for DHCHAP secrets

The DHCHAP secrets (dhchap_secret and dhchap_ctrl_secret) contain
authentication key material for NVMe-oF. Use kfree_sensitive() instead
of kfree() in nvmf_free_options() to ensure secrets are zeroed before
the memory is freed, preventing recovery from freed pages.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Daniel Hodges <hodgesd@meta.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>