Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Set volume device name to sdc

    Functest is now using scsi volume type for fuel
    Set correct volume device name for functest volume tests

    JIRA: ARMBAND-402

    Change-Id: I2265901eeb624a395388f6ce8afae226b129c5be
    Signed-off-by: Delia Popescu <delia.popescu@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 650b54a..f7f3623 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 650b54aeead7eee047ed17eacb4bc401c936a0aa
+Subproject commit f7f3623807c6ff914b28e89b157e3c9e3578d507