ide: add IDE_HFLAG_4DRIVES host flag

Add IDE_HFLAG_4DRIVES host flag and use it instead of ide_4drives
chipset type in ide_init_port().

There should be no functional changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-4drives.c b/drivers/ide/ide-4drives.c
index 9e85b1e..78aca75 100644
--- a/drivers/ide/ide-4drives.c
+++ b/drivers/ide/ide-4drives.c
@@ -23,7 +23,8 @@
 
 static const struct ide_port_info ide_4drives_port_info = {
 	.port_ops		= &ide_4drives_port_ops,
-	.host_flags		= IDE_HFLAG_SERIALIZE | IDE_HFLAG_NO_DMA,
+	.host_flags		= IDE_HFLAG_SERIALIZE | IDE_HFLAG_NO_DMA |
+				  IDE_HFLAG_4DRIVES,
 };
 
 static int __init ide_4drives_init(void)