hisi_sas: use platform_get_irq()

It is preferred that drivers use platform_get_irq() instead of
irq_of_parse_and_map(), so replace.

Signed-off-by: John Garry <john.garry@huawei.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>