[SCSI] iscsi class: sysfs group is_visible callout for session attrs

The iscsi class currently does not support writable sysfs
attrs for LLD sysfs settings. This patch converts the
iscsi class and driver's session attrs to use the attribute
container sysfs group and the sysfs group's is_visible callout
to be able to support readable or writable sysfs attrs.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h
index 8918329..53eb938 100644
--- a/include/scsi/scsi_transport_iscsi.h
+++ b/include/scsi/scsi_transport_iscsi.h
@@ -86,7 +86,6 @@
 	char *name;
 	unsigned int caps;
 	/* LLD sets this to indicate what values it can export to sysfs */
-	uint64_t param_mask;
 	uint64_t host_param_mask;
 	uint64_t iface_param_mask;
 
@@ -219,6 +218,9 @@
 #define iscsi_dev_to_session(_dev) \
 	container_of(_dev, struct iscsi_cls_session, dev)
 
+#define transport_class_to_session(_cdev) \
+	iscsi_dev_to_session(_cdev->parent)
+
 #define iscsi_session_to_shost(_session) \
 	dev_to_shost(_session->dev.parent)