Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Merge "prototypes: xci: xci-deploy: Set default value for devel parameters"
  - prototypes: xci: xci-deploy: Set default value for devel parameters

    Commit 68412ffc734e ("prototypes: xci: xci-deploy.sh: Append trailing
    slash for rsync vars") modified xci-deploy.sh script to append a
    trailing slash to the devel variables but it broke the script when
    one of these variables was not set (since we run with 'set -eu') with
    the following error:

    ./xci-deploy.sh: line 45: !local_user_var: unbound variable

    Fixes: I0103b754585931fa1dcd3966c52d7e4a8f2f63f6
    Change-Id: Ic2465ff07348b61e74e191516425cd10d80c1fce
    Signed-off-by: Markos Chandras <mchandras@suse.de>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 7a17287..4aa5759 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 7a17287a071eec33bc0cd542230dce9d2dc8129b
+Subproject commit 4aa57598753b07ed62b3524766ef4d158ba9c5fd