[SCSI] scsi_transport_iscsi: Add flash node mgmt support

This patch allows iscsiadm to manage iSCSI target information stored on
adapter flash on per host basis.

The sysfs entries will look as cited below:
	/sys/bus/iscsi_flashnode/devices/flashnode_sess-<host_no>:<flashnode_id>/<session attrs>
	/sys/bus/iscsi_flashnode/devices/flashnode_conn-<host_no>:<flashnode_id>:<conn_id>/<conn attrs>

Signed-off-by: Adheer Chandravanshi <adheer.chandravanshi@qlogic.com>
Signed-off-by: Manish Rangankar <manish.rangankar@qlogic.com>
Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>