Add irq_flags to struct pata_platform_info

On some embedded platforms, such as blackfin, the gpio interrupt for
IDE interface is designed to be triggered with high voltage. The gpio
port should be configured properly by set_irq_type() when register
the irq. This patch enable the generic pata platform driver to
accept platform irq flags data.

Signed-off-by: Sonic Zhang <sonic.adi@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>