ide: add IDE_HFLAG_BOOTABLE host flag

Add IDE_HFLAG_BOOTABLE host flag and IDE_HFLAG_OFF_BOARD define.  Convert
all host drivers using ide_pci_device_t to use IDE_HFLAG_{BOOTABLE,OFF_BOARD}
instead of d->bootable and then remove no longer needed d->bootable.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/piix.c b/drivers/ide/pci/piix.c
index 3694db6..287f4e3 100644
--- a/drivers/ide/pci/piix.c
+++ b/drivers/ide/pci/piix.c
@@ -417,7 +417,7 @@
 		.init_hwif	= init_hwif_piix,	\
 		.autodma	= AUTODMA,		\
 		.enablebits	= {{0x41,0x80,0x80}, {0x43,0x80,0x80}}, \
-		.bootable	= ON_BOARD,		\
+		.host_flags	= IDE_HFLAG_BOOTABLE,	\
 		.pio_mask	= ATA_PIO4,		\
 		.udma_mask	= udma,			\
 	}
@@ -436,8 +436,7 @@
 		.init_hwif	= init_hwif_piix,
 		.autodma	= NODMA,
 		.enablebits	= {{0x6d,0xc0,0x80}, {0x6d,0xc0,0xc0}},
-		.bootable	= ON_BOARD,
-		.host_flags	= IDE_HFLAG_ISA_PORTS,
+		.host_flags	= IDE_HFLAG_ISA_PORTS | IDE_HFLAG_BOOTABLE,
 		.pio_mask	= ATA_PIO4,
 	},