scsi: hisi_sas: Add support for interrupt coalescing for v3 hw

If INT_COAL_EN is enabled, configure time and count of interrupt
coalescing.  Then if CQ collects count of CQ entries in time, it will
report the interrupt. Or if CQ doesn't collect enough CQ entries in time,
it will report the interrupt at timeout.

As all the registers are not supported to be changed dynamically, we need
to config those register between disable and enable PHYs.

Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>