Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Merge "vswitches/ovs: delete bridges on stop"
  - vswitches/ovs: delete bridges on stop

    On stop, remove all created bridges in order to clean the working
    environment.

    Moreover, when an OVS bridge is deleted, remove also all attached ports.

    By the way, as the context manager of OFBridge is never used by the
    current test implementation and by any OVS vswitches in order to manage
    their creation/deletion, let's remove this dead code.

    JIRA: VSPERF-570

    Change-Id: I7ce62d56a8a2fe7b45e693f3c2dd91e1b435567c
    Signed-off-by: Julien Meunier <julien.meunier@6wind.com>

diff --git a/docs/submodules/vswitchperf b/docs/submodules/vswitchperf
index 7440717..446e4c1 160000 (submodule)
--- a/docs/submodules/vswitchperf
+++ b/docs/submodules/vswitchperf
@@ -1 +1 @@
-Subproject commit 7440717327dabe7ae37f99cb060bce43a7878096
+Subproject commit 446e4c14c7f91b797a338db94b9bcb32b1c7d229