Preface the "asserting atn" diagnostic with controller/target information.

Restore a call to ahc_assert_atn() that was inadvertantly lost when the
asserting atn diagnostic was added.  This, among other things, resulted
in driver negotiation failures with devices that initiated negotiation
(e.g. most IBM drives). 

drivers/scsi/aic7xxx/aic7xxx_core.c

@@ -37,7 +37,7 @@
  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGES.
  *
- * $Id: //depot/aic7xxx/aic7xxx/aic7xxx.c#104 $
+ * $Id: //depot/aic7xxx/aic7xxx/aic7xxx.c#105 $
  *
  * $FreeBSD$
  */
@@ -2772,9 +2772,12 @@ ahc_handle_message_phase(struct ahc_softc *ahc)
 			 */
 			if (ahc->msgout_len != 0) {
 #ifdef AHC_DEBUG
-				if ((ahc_debug & AHC_SHOW_MESSAGES) != 0)
+				if ((ahc_debug & AHC_SHOW_MESSAGES) != 0) {
+					ahc_print_devinfo(ahc, &devinfo);
 					printf("Asserting ATN for response\n");
+				}
 #endif
+				ahc_assert_atn(ahc);
 			}
 		} else 
 			ahc->msgin_index++;