Update git submodules

* Update docs/submodules/nfvbench from branch 'stable/euphrates'
  - Build container with opnfv-5.0.1

    Change-Id: Id1101f6ca79d3a1043bd3ba684d6660f089647c5
    Signed-off-by: ahothan <ahothan@cisco.com>

diff --git a/docs/submodules/nfvbench b/docs/submodules/nfvbench
index cf170f0..15526eb 160000 (submodule)
--- a/docs/submodules/nfvbench
+++ b/docs/submodules/nfvbench
@@ -1 +1 @@
-Subproject commit cf170f046d63f61819ab6b5a2c75b078bf34be82
+Subproject commit 15526ebdbc5c97e6d26c95e4187ddeeda5cc9d3f