fix uninitialized variable warnings

extras/usb_id/usb_id.c

@@ -368,7 +368,7 @@ int main(int argc, char **argv)
 		{}
 	};
 	struct udev *udev;
-	struct udev_device *dev;
+	struct udev_device *dev = NULL;
 	char syspath[UTIL_PATH_SIZE];
 	const char *devpath;
 	static int export;

udev/udevadm-settle.c

@@ -41,7 +41,7 @@ int udevadm_settle(struct udev *udev, int argc, char *argv[])
 		{}
 	};
 	int timeout = DEFAULT_TIMEOUT;
-	struct udev_queue *udev_queue;
+	struct udev_queue *udev_queue = NULL;
 	int loop;
 	int rc = 0;