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/arm/ide_arm.c b/drivers/ide/arm/ide_arm.c
index 4263ffd..2f311da 100644
--- a/drivers/ide/arm/ide_arm.c
+++ b/drivers/ide/arm/ide_arm.c
@@ -49,6 +49,7 @@
 	memset(&hw, 0, sizeof(hw));
 	ide_std_init_ports(&hw, base, ctl);
 	hw.irq = IDE_ARM_IRQ;
+	hw.chipset = ide_generic;
 
 	hwif = ide_find_port();
 	if (hwif) {