Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "[storperf] Fix stable/fraser branch name"
  - [storperf] Fix stable/fraser branch name

    Missed changing the branch name when copying over the release file.

    Change-Id: I25105253911f19dbfa621b29c2a812df4a8af01d
    Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index b74272c..a6c908b 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit b74272cbaab1537b9b1facaeb74c1e548bdb32d6
+Subproject commit a6c908b3bd7e698ab2c593604b0141276fc77f3e