Update git submodules

* Update platform/frameworks/base from branch 'master'
  to cbb2fa2f004366538d9452698db80bd1971cbf76
  - Merge "Allow VPN apps to ask for running the validation checks"
  - Allow VPN apps to ask for running the validation checks
    
    Expose an API to allow VPNs app to ask for running the validation
    check on the VPN network built from Ikev2VpnProfile.
    
    Bug: 184750836
    Test: New test in Ikev2VpnTest
          Also FrameworksNetTests
    Change-Id: I385bb887b6c697d8f5d87af750dbd2aab44afca6
    CTS-Coverage-Bug: 184750836
     (but CTS is in the same topic, just not detected by the tool)