ibmvscsis: Add SGL limit

BugLink: http://bugs.launchpad.net/bugs/1662551

This patch adds internal LIO sgl limit since the driver already
sets a max transfer limit on transport layer of 1MB to the client.

Cc: stable@vger.kernel.org
Tested-by: Steven Royer <seroyer@linux.vnet.ibm.com>
Signed-off-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
(cherry picked from commit b22bc278)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c

@@ -3818,6 +3818,7 @@ static struct configfs_attribute *ibmvscsis_tpg_attrs[] = {
 static const struct target_core_fabric_ops ibmvscsis_ops = {
 	.module				= THIS_MODULE,
 	.name				= "ibmvscsis",
+	.max_data_sg_nents		= MAX_TXU / PAGE_SIZE,
 	.get_fabric_name		= ibmvscsis_get_fabric_name,
 	.tpg_get_wwn			= ibmvscsis_get_fabric_wwn,
 	.tpg_get_tag			= ibmvscsis_get_tag,