tcm_qla2xxx Add SCSI command jammer/discard capability

This patch introduces support for TCM_QLA2XXX_DEBUG and
associated tcm_qla2xxx_tpg->tpg_attrib.jam_host checking
used to test dropped packets to FC host environments.

Tested by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Laurence Oberman <loberman@redhat.com>
Acked-by: Himanshu Madhani <himanshu.madhani@qlogic.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>