Update git submodules

* Update docs/submodules/sdc.git from branch 'master'
  to 51a0f7b4a6c924c42955fa93042bd154cb636a16
  - common code coverage increase
    
    Add tests for classes in sdc.tosca.datatypes.model package
    
    Change-Id: Ifc277512d833b2501f0e594b9062d39c26565055
    Issue-ID: SDC-2326
    Signed-off-by: Piotr Darosz <piotr.darosz@nokia.com>
    
1 file changed