Update git submodules

* Update docs/submodules/samplevnf from branch 'stable/fraser'
  - Fix potential crash with latency accuracy

    Detect, remember and skip bad/unexpected packets:
    - too short to hold the latency-related values
    - with bad signature
    - with invalid generator_id
    using a uint64_t-based bitmap.

    Also moved variable declarations closer to usage,
    added some likely/unlikely hints,
    reworked some return statements, and
    fixed 32-bit overflow (every ~4s) of rx_time_err computation.

    Change-Id: Ib2aadc1af6b7a68601cc080ba66b10d41ff9a64e
    Signed-off-by: Patrice Buriez <patrice.buriez@intel.com>

diff --git a/docs/submodules/samplevnf b/docs/submodules/samplevnf
index 692702c..fc6a837 160000 (submodule)
--- a/docs/submodules/samplevnf
+++ b/docs/submodules/samplevnf
@@ -1 +1 @@
-Subproject commit 692702c10772e13b533c908ed3f95a430ad476ce
+Subproject commit fc6a8370e48cdf5fc9a77ab8e428c00c7b3e4093