ide: fix host drivers missing hwif->chipset initialization

ide_find_port() now depends on ->chipset being set for occupied ide_hwifs[]
slots so all host drivers have to initialize hwif->chipset properly.

This patch fixes a regression on hosts with > 1 port or with a single port
but no devices attached to it for an affected host drivers.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/legacy/q40ide.c b/drivers/ide/legacy/q40ide.c
index 6f535d0..8ff6e2d 100644
--- a/drivers/ide/legacy/q40ide.c
+++ b/drivers/ide/legacy/q40ide.c
@@ -70,6 +70,8 @@
 
 	hw->irq = irq;
 	hw->ack_intr = ack_intr;
+
+	hw->chipset = ide_generic;
 }
 
 static void q40ide_input_data(ide_drive_t *drive, struct request *rq,