Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "vswitchperf: python version change"
  - vswitchperf: python version change

    In order to execute VSPERF CI job, the SCL with python3 must
    be enabled. Recently SCL command was changed to enable python3.4.

    Change-Id: I4cf34ff28db2c789f4bc13116ed2d5d95eb81990
    Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
    Reviewed-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>
    Reviewed-by: Christian Trautman <ctrautma@redhat.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 705dc15..7cfca02 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 705dc15a141f84f4a746cb4699b59e8adde3119e
+Subproject commit 7cfca0241ee89c6d162a0c810d41b31e8cec95d0