qla2xxx: Add flush after updating ATIOQ consumer index.

qla2xxx: Add flush after updating ATIOQ consumer index.

Orabug: 26844197, 26923029

After updating the consumer index of ATIO Q, a read is
required to flush the write to the adapter register.

Signed-off-by: Quinn Tran <quinn.tran@qlogic.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@qlogic.com>
Reviewed-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Brian Maly <brian.maly@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>