scsi: hisi_sas: Fix IRQ checks

Commit df2d8213 ("hisi_sas: use platform_get_irq()") failed to take
into account that irq_of_parse_and_map() and platform_get_irq() have a
different way of indicating an error: the former returns 0 and the latter
returns a negative error code. Fix up the IRQ checks!

Link: https://lore.kernel.org/r/810f26d3-908b-1d6b-dc5c-40019726baca@omprussia.ru


Fixes: df2d8213 ("hisi_sas: use platform_get_irq()")
Acked-by: John Garry <john.garry@huawei.com>
Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>