target: make the tpg_get_default_depth method optional

All fabric drivers except for iSCSI always return 1, so implement
that as default behavior.

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

drivers/xen/xen-scsiback.c

@@ -1292,11 +1292,6 @@ static u16 scsiback_get_tag(struct se_portal_group *se_tpg)
 	return tpg->tport_tpgt;
 }
 
-static u32 scsiback_get_default_depth(struct se_portal_group *se_tpg)
-{
-	return 1;
-}
-
 static u32
 scsiback_get_pr_transport_id(struct se_portal_group *se_tpg,
 			      struct se_node_acl *se_nacl,
@@ -1950,7 +1945,6 @@ static const struct target_core_fabric_ops scsiback_ops = {
 	.get_fabric_proto_ident		= scsiback_get_fabric_proto_ident,
 	.tpg_get_wwn			= scsiback_get_fabric_wwn,
 	.tpg_get_tag			= scsiback_get_tag,
-	.tpg_get_default_depth		= scsiback_get_default_depth,
 	.tpg_get_pr_transport_id	= scsiback_get_pr_transport_id,
 	.tpg_get_pr_transport_id_len	= scsiback_get_pr_transport_id_len,
 	.tpg_parse_pr_out_transport_id	= scsiback_parse_pr_out_transport_id,