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/scc_pata.c b/drivers/ide/pci/scc_pata.c
index ac519fa..1784ac2 100644
--- a/drivers/ide/pci/scc_pata.c
+++ b/drivers/ide/pci/scc_pata.c
@@ -705,8 +705,8 @@
       .init_iops	= init_iops_scc,		\
       .init_hwif	= init_hwif_scc,		\
       .autodma	= AUTODMA,				\
-      .bootable	= ON_BOARD,				\
-      .host_flags	= IDE_HFLAG_SINGLE,		\
+      .host_flags	= IDE_HFLAG_SINGLE |		\
+			  IDE_HFLAG_BOOTABLE,		\
       .pio_mask		= ATA_PIO4,			\
   }