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/amd74xx.c b/drivers/ide/pci/amd74xx.c
index 824471f..7dbc692 100644
--- a/drivers/ide/pci/amd74xx.c
+++ b/drivers/ide/pci/amd74xx.c
@@ -92,7 +92,7 @@
 
 	ide_timing_compute(drive, speed, &t, T, UT);
 
-	if (peer->present) {
+	if (peer->dev_flags & IDE_DFLAG_PRESENT) {
 		ide_timing_compute(peer, peer->current_speed, &p, T, UT);
 		ide_timing_merge(&p, &t, &t, IDE_TIMING_8BIT);
 	}