Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "lib.sh: Skip modprobing nbd, loop if inbuilt"
  - lib.sh: Skip modprobing nbd, loop if inbuilt

    While at it, skip waiting for Salt master when deleting UEFI stale
    entries if it doesn't respond to ping.

    Also, use https for fetching Armband GPG key to bypass yet another
    hks issue behind proxies/firewalls that block hks port.

    Change-Id: I400cbe3257094b62c96b302a3c81c5ffd1ba4755
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index f45309a..ab31c13 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit f45309a760e04597bdb379f3c7a1c0a2b28e1f87
+Subproject commit ab31c13580dc51bb95d07627da5b19216ef2edff