ide: add device flags

Add 'unsigned long dev_flags' to ide_drive_t and convert bitfields
to IDE_DFLAG_* flags.

While at it:
- IDE_DFLAG_ADDRESSING -> IDE_DFLAG_LBA48
- fixup some comments
- remove needless g->flags zeroing from ide*_probe()

There should be no functional changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/sc1200.c b/drivers/ide/pci/sc1200.c
index bdc1fed..50405ed 100644
--- a/drivers/ide/pci/sc1200.c
+++ b/drivers/ide/pci/sc1200.c
@@ -216,7 +216,8 @@
 	if (mode != -1) {
 		printk("SC1200: %s: changing (U)DMA mode\n", drive->name);
 		ide_dma_off_quietly(drive);
-		if (ide_set_dma_mode(drive, mode) == 0 && drive->using_dma)
+		if (ide_set_dma_mode(drive, mode) == 0 &&
+		    (drive->dev_flags & IDE_DFLAG_USING_DMA))
 			hwif->dma_ops->dma_host_set(drive, 1);
 		return;
 	}