ACPI: work around duplicate name "VID" problem on T61

This can only fix the problem that more than one video bus device
have the same AML name "VID".
ie. the proc I/F for the second "VID" video bus device is located under
/proc/acpi/video/VID1/...

As this is really rare and the ACPI proc I/F is a legacy feature that
we are planning to remove.
We won't provide a generic solution for this problem.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/video.c

@@ -1833,6 +1833,7 @@ static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)
 	return;
 }
 
+static int instance;
 static int acpi_video_bus_add(struct acpi_device *device)
 {
 	int result = 0;
@@ -1847,6 +1848,13 @@ static int acpi_video_bus_add(struct acpi_device *device)
 	if (!video)
 		return -ENOMEM;
 
+	/* a hack to fix the duplicate name "VID" problem on T61 */
+	if (!strcmp(device->pnp.bus_id, "VID")) {
+		if (instance)
+			device->pnp.bus_id[3] = '0' + instance;
+		instance ++;
+	}
+
 	video->device = device;
 	strcpy(acpi_device_name(device), ACPI_VIDEO_BUS_NAME);
 	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);