nvmet: add tracing of authentication commands

Add nvme_fabrics_type_auth_send and nvme_fabrics_type_auth_receive
to the nvme target's tracing facility.

Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>