tipc: Fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning
by explicitly adding a break statement instead of letting the code fall
through to the next case.

Link: https://github.com/KSPP/linux/issues/115Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

net/tipc/link.c

@@ -649,6 +649,7 @@ int tipc_link_fsm_evt(struct tipc_link *l, int evt)
 			break;
 		case LINK_FAILOVER_BEGIN_EVT:
 			l->state = LINK_FAILINGOVER;
+			break;
 		case LINK_FAILURE_EVT:
 		case LINK_RESET_EVT:
 		case LINK_ESTABLISH_EVT: