ide: add IDE_HFLAG_LEGACY_IRQS host flag

Add IDE_HFLAG_LEGACY_IRQS host flag to tell ide_pci_setup_ports() to set
hwif->irq to legacy IRQ 14/15 (iff hwif->irq is not already set) and convert
atiixp, piix, serverworks, sis5513 and slc90e66 host drivers to use it.

While at it:

* In piix.c add IDE_HFLAGS_PIIX define and don't use ->init_hwif for MPIIX.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/slc90e66.c b/drivers/ide/pci/slc90e66.c
index 416fbab..d85a48e 100644
--- a/drivers/ide/pci/slc90e66.c
+++ b/drivers/ide/pci/slc90e66.c
@@ -133,9 +133,6 @@
 	u8 reg47 = 0;
 	u8 mask = hwif->channel ? 0x01 : 0x02;  /* bit0:Primary */
 
-	if (!hwif->irq)
-		hwif->irq = hwif->channel ? 15 : 14;
-
 	hwif->set_pio_mode = &slc90e66_set_pio_mode;
 	hwif->set_dma_mode = &slc90e66_set_dma_mode;
 
@@ -156,7 +153,7 @@
 	.name		= "SLC90E66",
 	.init_hwif	= init_hwif_slc90e66,
 	.enablebits	= {{0x41,0x80,0x80}, {0x43,0x80,0x80}},
-	.host_flags	= IDE_HFLAG_BOOTABLE,
+	.host_flags	= IDE_HFLAG_LEGACY_IRQS | IDE_HFLAG_BOOTABLE,
 	.pio_mask	= ATA_PIO4,
 	.swdma_mask	= ATA_SWDMA2_ONLY,
 	.mwdma_mask	= ATA_MWDMA12_ONLY,