hisi_sas: add v2 channel interrupt handler

This also includes broadcast handler. Unlike v1 hw, broadcast does not
have its own dedicated interrupt.

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>