Use __FBSDID() as per style(9).

sys/dev/en/midway.c

@@ -31,9 +31,9 @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- * $FreeBSD$
  */
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
 
 /*
  *