Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "AArch64: Switch back to hwe-16.04 kernel"
  - AArch64: Switch back to hwe-16.04 kernel

    Align kernel versions across architectures (where possible).

    Change-Id: I66a822611eb5e46f90b62f5d36df571ae75dcba3
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index f29966d..8a5df5e 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit f29966ddead2ba5f97d385108e19d1889cc7b48e
+Subproject commit 8a5df5e7f886cfa27260d62a963fb0cb60d346ff