Add missing break in BaseServingState

The break is missing when processing CMD_SERVICE_FAILED_TO_START
in BaseServingState.

Test: atest TetheringTests
Change-Id: I1699da251f90ec447466266b704df24d081c40b3
diff --git a/Tethering/src/android/net/ip/IpServer.java b/Tethering/src/android/net/ip/IpServer.java
index b807544..b4c1b8a 100644
--- a/Tethering/src/android/net/ip/IpServer.java
+++ b/Tethering/src/android/net/ip/IpServer.java
@@ -1148,6 +1148,7 @@
                 case CMD_SERVICE_FAILED_TO_START:
                     mLog.e("start serving fail, error: " + message.arg1);
                     transitionTo(mInitialState);
+                    break;
                 default:
                     return false;
             }