[PATCH] USB: check for device in zd1201_resume

My patch adding PM support for zd1201 didn't check for the device on
resume, which can oops if the device has been removed.

This patch fixes it.
Signed-off-by: NColin Leroy <colin@colino.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/net/zd1201.c

@@ -1905,6 +1905,9 @@ static int zd1201_resume(struct usb_interface *interface)
 {
 	struct zd1201 *zd = usb_get_intfdata(interface);
 
+	if (!zd || !zd->dev)
+		return -ENODEV;
+
 	netif_device_attach(zd->dev);
 
 	if (zd->was_enabled)