Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "virtual: odl-router: Stop overriding Ubuntu repos"
  - virtual: odl-router: Stop overriding Ubuntu repos

    Keep UCA default apt sources, instead of overriding them with arch
    specific values from:
    - system.linux.system.repo.ubuntu

    Change-Id: I1edc725a97ae6290d316a7916c27fd904f59db04
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 7758d6f..80757cc 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 7758d6f9fcaa61091c6970d246a9905436aef06b
+Subproject commit 80757cccc9e6e3edefc6fa4562d22321486e8ec8