libata: add another IRQ calls (libata drivers)

This patch is against each libata driver.

Two IRQ calls are added in ata_port_operations.
- irq_on() is used to enable interrupts.
- irq_ack() is used to acknowledge a device interrupt.

In most drivers, ata_irq_on() and ata_irq_ack() are used for
irq_on and irq_ack respectively.

In some drivers (ex: ahci, sata_sil24) which cannot use them
as is, ata_dummy_irq_on() and ata_dummy_irq_ack() are used.

Signed-off-by: Kou Ishizaki <kou.ishizaki@toshiba.co.jp>
Signed-off-by: Akira Iguchi <akira2.iguchi@toshiba.co.jp>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/sata_uli.c

@@ -117,6 +117,8 @@ static const struct ata_port_operations uli_ops = {
 
 	.irq_handler		= ata_interrupt,
 	.irq_clear		= ata_bmdma_irq_clear,
+	.irq_on			= ata_irq_on,
+	.irq_ack		= ata_irq_ack,
 
 	.scr_read		= uli_scr_read,
 	.scr_write		= uli_scr_write,