Update git submodules

* Update docs/submodules/multicloud/k8s.git from branch 'master'
  to b3df7a557a37cf60a4d549a60651897ef3411b34
  - Merge "Adapt network plugin to interface restrictions"
  - Adapt network plugin to interface restrictions

    Network plugin was not fully compliant with interface it should
    implement due to type of one function argument. Relevant functions
    have been adapted to utilize proper types.

    Issue-ID: MULTICLOUD-708

    Signed-off-by: Konrad Bańka <k.banka@samsung.com>
    Change-Id: Ic619ad476dba5e6582759290e18edceaa98c332f