Clean up the onClatInterfaceStateUpdate() in IpClient

* Remove the unnecessary comment.
* Remove the redundant mClatInterfaceExists in IpClientLinkObserver and
  use mHasClatInterface in IpClient to handle the duplicated event.

Test: TH
Change-Id: I81794e97d6850d09847bec9a59d248b60db5bb3f
2 files changed