ide-acpi: add missing drive->acpidata zeroing

There should be no functionality changes caused by this patch.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-acpi.c b/drivers/ide/ide-acpi.c
index e07b189..0f6fb6b7 100644
--- a/drivers/ide/ide-acpi.c
+++ b/drivers/ide/ide-acpi.c
@@ -710,6 +710,8 @@
 	for (i = 0; i < MAX_DRIVES; i++) {
 		drive = &hwif->drives[i];
 
+		memset(drive->acpidata, 0, sizeof(*drive->acpidata));
+
 		if (!drive->present)
 			continue;