isci: Manage the IREQ_NO_AUTO_FREE_TAG under scic_lock.

Since there is a possibilty of a timeout waiting for the RNC suspension,
handle the exit case from the task termination under scic_lock, and leave
the tag allocated if the termination timed-out.

Signed-off-by: Jeff Skirvin <jeffrey.d.skirvin@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>