s390/net: Mark expected switch fall-throughs

Mark switch cases where we are expecting to fall through.

This patch fixes the following warnings (Building: s390):

drivers/s390/net/ctcm_fsms.c: In function ‘ctcmpc_chx_attnbusy’:
drivers/s390/net/ctcm_fsms.c:1703:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (grp->changed_side == 1) {
      ^
drivers/s390/net/ctcm_fsms.c:1707:2: note: here
  case MPCG_STATE_XID0IOWAIX:
  ^~~~

drivers/s390/net/ctcm_mpc.c: In function ‘ctc_mpc_alloc_channel’:
drivers/s390/net/ctcm_mpc.c:358:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (callback)
      ^
drivers/s390/net/ctcm_mpc.c:360:2: note: here
  case MPCG_STATE_XID0IOWAIT:
  ^~~~

drivers/s390/net/ctcm_mpc.c: In function ‘mpc_action_timeout’:
drivers/s390/net/ctcm_mpc.c:1469:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if ((fsm_getstate(rch->fsm) == CH_XID0_PENDING) &&
      ^
drivers/s390/net/ctcm_mpc.c:1472:2: note: here
  default:
  ^~~~~~~
drivers/s390/net/ctcm_mpc.c: In function ‘mpc_send_qllc_discontact’:
drivers/s390/net/ctcm_mpc.c:2087:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (grp->estconnfunc) {
      ^
drivers/s390/net/ctcm_mpc.c:2092:2: note: here
  case MPCG_STATE_FLOWC:
  ^~~~

drivers/s390/net/qeth_l2_main.c: In function ‘qeth_l2_process_inbound_buffer’:
drivers/s390/net/qeth_l2_main.c:328:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
    if (IS_OSN(card)) {
       ^
drivers/s390/net/qeth_l2_main.c:337:3: note: here
   default:
   ^~~~~~~
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

drivers/s390/net/ctcm_fsms.c

@@ -1704,6 +1704,7 @@ static void ctcmpc_chx_attnbusy(fsm_instance *fsm, int event, void *arg)
 			grp->changed_side = 2;
 			break;
 		}
+		/* Else, fall through */
 	case MPCG_STATE_XID0IOWAIX:
 	case MPCG_STATE_XID7INITW:
 	case MPCG_STATE_XID7INITX:

drivers/s390/net/ctcm_mpc.c

@@ -357,6 +357,7 @@ int ctc_mpc_alloc_channel(int port_num, void (*callback)(int, int))
 		/*fsm_newstate(grp->fsm, MPCG_STATE_XID2INITW);*/
 		if (callback)
 			grp->send_qllc_disc = 1;
+		/* Else, fall through */
 	case MPCG_STATE_XID0IOWAIT:
 		fsm_deltimer(&grp->timer);
 		grp->outstanding_xid2 = 0;
@@ -1469,6 +1470,7 @@ static void mpc_action_timeout(fsm_instance *fi, int event, void *arg)
 		if ((fsm_getstate(rch->fsm) == CH_XID0_PENDING) &&
 		   (fsm_getstate(wch->fsm) == CH_XID0_PENDING))
 			break;
+		/* Else, fall through */
 	default:
 		fsm_event(grp->fsm, MPCG_EVENT_INOP, dev);
 	}
@@ -2089,6 +2091,7 @@ static int mpc_send_qllc_discontact(struct net_device *dev)
 			grp->estconnfunc = NULL;
 			break;
 		}
+		/* Else, fall through */
 	case MPCG_STATE_FLOWC:
 	case MPCG_STATE_READY:
 		grp->send_qllc_disc = 2;

drivers/s390/net/qeth_l2_main.c

@@ -333,7 +333,7 @@ static int qeth_l2_process_inbound_buffer(struct qeth_card *card,
 				card->osn_info.data_cb(skb);
 				break;
 			}
-			/* else unknown */
+			/* Else, fall through */
 		default:
 			dev_kfree_skb_any(skb);
 			QETH_CARD_TEXT(card, 3, "inbunkno");