ide: merge ide_hwgroup_t with ide_hwif_t (v2)

* Merge ide_hwgroup_t with ide_hwif_t.

* Cleanup init_irq() accordingly, then remove no longer needed
  ide_remove_port_from_hwgroup() and ide_ports[].

* Remove now unused HWGROUP() macro.

While at it:

* ide_dump_ata_error() fixups

v2:
* Fix ->quirk_list check in do_ide_request()
  (s/hwif->cur_dev/prev_port->cur_dev).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/sgiioc4.c b/drivers/ide/sgiioc4.c
index a687a7d..c68b71b 100644
--- a/drivers/ide/sgiioc4.c
+++ b/drivers/ide/sgiioc4.c
@@ -492,7 +492,7 @@
 
 static int sgiioc4_dma_setup(ide_drive_t *drive)
 {
-	struct request *rq = HWGROUP(drive)->rq;
+	struct request *rq = drive->hwif->rq;
 	unsigned int count = 0;
 	int ddir;