Update git submodules

Update git submodules

* Update docs/submodules/vswitchperf from branch 'stable/euphrates'
  - Merge "docs: Remove IETF drafts" into stable/euphrates
  - docs: Remove IETF drafts

    Removed drafts of test specification now published as RFC8204. Also removed IETF license notice and added
    a file with link to RFC8204

    Change-Id: I44b4cb75afeff74a58f402a7cb8816ddfbe52b87
    Signed-off-by: Trevor Cooper <trevor.cooper@intel.com>
    Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
    (cherry picked from commit c17fe61eba519ca1c49aee2214438f1a248fe9f8)