Update git submodules

* Update docs/submodules/fuel from branch 'stable/euphrates'
  - states: Split virtual_control_plane from maas

    We should eventually also support baremetal deploys without a
    virtualized control plane (VCP), so decouple MaaS provisioning
    from VCP provisioning.

    While at it, move "wait_for" bash function from maas state to
    common library file, lib.sh.

    Change-Id: I32c33135655cb6aceae901a5f92b51265a8c84b4
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit ebd7067904b36ae32566da63e433365948a1f973)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 139aacf..ea64dc2 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 139aacf390d38b60f4fe4fd618a0bcf6b54b35cf
+Subproject commit ea64dc22ea171d45ae60aff682fcadf9d525889b