Update git submodules

* Update docs/submodules/clamp.git from branch 'master'
  to 64d4727e2bb0973cf61a125fed240c8c4952d6ff
  - Fix legacy policy payload

    Ensure payload attribute is well not present if defined as an empty
    string

    Issue-ID: CLAMP-484
    Change-Id: If6d558c009dd695bfd5f83cf0d50800e12026121
    Signed-off-by: sebdet <sebastien.determe@intl.att.com>

diff --git a/docs/submodules/clamp.git b/docs/submodules/clamp.git
index 156d6ea..64d4727 160000 (submodule)
--- a/docs/submodules/clamp.git
+++ b/docs/submodules/clamp.git
@@ -1 +1 @@
-Subproject commit 156d6eac7960290fced027f4211974668ffa1d44
+Subproject commit 64d4727e2bb0973cf61a125fed240c8c4952d6ff