Update git submodules

* Update docs/submodules/daisy from branch 'master'
  - Remove iptables rules only in virtual deployment

    There are error messages "iptables: No chain/target/match by that name"
    in baremetal deployment:
    https://build.opnfv.org/ci/job/daisy-deploy-daily-master/298/console

    Change-Id: I7e2940222fd0a99ee42823a08a285bdd93892fe6
    Signed-off-by: Alex Yang <yangyang1@zte.com.cn>

diff --git a/docs/submodules/daisy b/docs/submodules/daisy
index d52f2ec..a6e2199 160000 (submodule)
--- a/docs/submodules/daisy
+++ b/docs/submodules/daisy
@@ -1 +1 @@
-Subproject commit d52f2ec25b346cceb9d0a9b400240d4baa0d7bdb
+Subproject commit a6e2199315356be5db8125ad26c2606186ba839c