target: Propigate up ->cmd_kref put return via transport_generic_free_cmd

Go ahead and propigate up the ->cmd_kref put return value from
target_put_sess_cmd() -> transport_release_cmd() -> transport_put_cmd()
-> transport_generic_free_cmd().

This is useful for certain fabrics when determining the active I/O
shutdown case with SCF_ACK_KREF where a final target_put_sess_cmd()
is still required by the caller.

Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h
index 8a26f0d..1dcce9c 100644
--- a/include/target/target_core_fabric.h
+++ b/include/target/target_core_fabric.h
@@ -114,7 +114,7 @@
 
 void	target_execute_cmd(struct se_cmd *cmd);
 
-void	transport_generic_free_cmd(struct se_cmd *, int);
+int	transport_generic_free_cmd(struct se_cmd *, int);
 
 bool	transport_wait_for_tasks(struct se_cmd *);
 int	transport_check_aborted_status(struct se_cmd *, int);