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/it8213.c b/drivers/ide/pci/it8213.c
index b52bca7..54fc0f4 100644
--- a/drivers/ide/pci/it8213.c
+++ b/drivers/ide/pci/it8213.c
@@ -193,8 +193,8 @@
 		.init_hwif	= init_hwif_it8213,	\
 		.autodma	= AUTODMA,		\
 		.enablebits	= {{0x41,0x80,0x80}}, \
-		.bootable	= ON_BOARD,		\
-		.host_flags	= IDE_HFLAG_SINGLE,	\
+		.host_flags	= IDE_HFLAG_SINGLE |	\
+				  IDE_HFLAG_BOOTABLE,	\
 		.pio_mask	= ATA_PIO4,		\
 	}