Update git submodules

* Update docs/submodules/functest from branch 'stable/gambia'
  - Temporarily disable Cinder volumes backup tests

    From the time being, all OPNFV installers [1][2][3] don't support
    Cinder volumes backup.

    We will find a better way to handle the lack of OPNFV requiremements
    (these tests pass succesfully in Orange Openlab).

    At least, it will allow verifying tempest_full in OPNFV gates.

    [1] Apex: https://artifacts.opnfv.org/logs/functest/lf-pod1/2018-10-25_02-17-25/tempest_full/tempest-report.html
    [2] Compass: https://artifacts.opnfv.org/logs/functest/huawei-virtual9/2018-10-24_04-54-25/tempest_full/tempest-report.html
    [3] Fuel: https://artifacts.opnfv.org/logs/functest/lf-pod2/gambia/2018-10-25_05-57-54/tempest_full/tempest-report.html

    Change-Id: I319536070aa77a5dbab6a692a1d76049f75e758b
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
    (cherry picked from commit 7cf46992c7f3e854b038f6f17a279d65108aa764)

  - Temporarily disable VNC tests

    At least Compass and Fuel configure Spice as console [1][2].
    It disables vnc testing as it could fail for endusers as well.

    [1] https://artifacts.opnfv.org/logs/functest/huawei-virtual9/2018-10-24_04-54-25/tempest_full/tempest-report.html
    [2] https://artifacts.opnfv.org/logs/functest/lf-pod2/gambia/2018-10-25_05-57-54/tempest_full/tempest-report.html

    Change-Id: I2a1ecf345cb81170c1b1a3e49f8f3a58602fc3f0
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
    (cherry picked from commit df9d5c5d3b80b613130de59a1810f7fce9cbbc0d)

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 24b16fd..7e897b2 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 24b16fde51b3db38d0795dd4390d2fee189c0d19
+Subproject commit 7e897b2dc054a6a3700ad20b470f4c2985cea8ae