linux-phytec-ti

tcm_qla2xxx: introduce a private sess_kref

This stops abusing the common sess_kref to overload it for private
usage, which allows removing the shutdown_session method as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>