scsi: qla2xxx: Enable ATIO interrupt handshake for ISP27XX

Enable ATIO Q interrupt handshake for ISP27XX. This patch
coalesce ATIO's interrupts for Quad port ISP27XX adapter.
Interrupt coalesce allows performance to scale for this
specific case.

Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>