ata: pata_platform: Add IRQF_SHARED to IRQ flags

It's quite possible that multiple devices can be hooked up
to the same interrupt line with the processor. So add IRQF_SHARED
in request irq.

Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>