Update git submodules

* Update docs/submodules/daisy from branch 'master'
  - Update OS image for target nodes

    During deployment of DPDK scenario for Queens, we encountered
    kernel panic and soft lock. Hope a Kernel upgrade may help.

    Change-Id: I741cc81fcce499a93832a5980f0ed2fd568f957f
    Signed-off-by: Zhijiang Hu <hu.zhijiang@zte.com.cn>

diff --git a/docs/submodules/daisy b/docs/submodules/daisy
index c314d9c..6a7ee18 160000 (submodule)
--- a/docs/submodules/daisy
+++ b/docs/submodules/daisy
@@ -1 +1 @@
-Subproject commit c314d9c3a5f522f9b2979ef03b218c852b72cfb3
+Subproject commit 6a7ee18538561c772b0bfbc48805e2a2de74a9c6