Update git submodules

Update git submodules

* Update docs/submodules/samplevnf from branch 'master'
  - Fix link speed when link is down at startup.

    When link is down at startup, the link_speed returned by DPDK
    is 0. This results in un-optimized latency estimates in gen and lat.
    With this fix, lat and gen do nothing until link_speed is
    properly initialized, and use the right link speed in the fast path.

    Change-Id: Id2d14b6966ccfac7cc78db3c5a74e704b42edae7
    Signed-off-by: Xavier Simonart <xavier.simonart@intel.com>