iscsi-target: Expose default_erl as TPG attribute

This patch exposes default_erl as a TPG attribute so that it may be
set TPG wide in demo-mode, but still allow the existing NodeACL
attribute to be overridden on a per initiator basis.

Reported-by: Arshad Hussain <arshad.hussain@calsoftinc.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/iscsi/iscsi_target_tpg.h b/drivers/target/iscsi/iscsi_target_tpg.h
index 3e8ce86..213c0fc 100644
--- a/drivers/target/iscsi/iscsi_target_tpg.h
+++ b/drivers/target/iscsi/iscsi_target_tpg.h
@@ -38,5 +38,6 @@
 extern int iscsit_ta_demo_mode_write_protect(struct iscsi_portal_group *, u32);
 extern int iscsit_ta_prod_mode_write_protect(struct iscsi_portal_group *, u32);
 extern int iscsit_ta_demo_mode_discovery(struct iscsi_portal_group *, u32);
+extern int iscsit_ta_default_erl(struct iscsi_portal_group *, u32);
 
 #endif /* ISCSI_TARGET_TPG_H */