Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - Add support for openSuse Tumbleweed

    This patch aims at adding support for Tumbleweed, which is
    a rolling release. That means that the VERSION_ID is not fixed
    and can't be mapped to a directory e.g
    - VERSION_ID="20171120"
    - VERSION_ID="20171121"

    Change-Id: I99c9a4f1042c22b73879e954147c54c87b6a8b21
    Signed-off-by: Jose Lausuch <jalausuch@suse.com>

diff --git a/docs/submodules/vswitchperf b/docs/submodules/vswitchperf
index 1dc9677..d1270fb 160000 (submodule)
--- a/docs/submodules/vswitchperf
+++ b/docs/submodules/vswitchperf
@@ -1 +1 @@
-Subproject commit 1dc96770c874ff9983c54502c56bf6137087a562
+Subproject commit d1270fb092fda14e02a306cfe7af160b45b2677c