Update git submodules

* Update docs/submodules/usecase-ui.git from branch 'master'
  to 8c7857b2f978ae0d19e95cc637eb4afe8fca6f96
  - Package management interface development
    
    Change-Id: I1e6a4688dcfa223e8916854442acc6e423556363
    Issue-ID: USECASEUI-211
    Signed-off-by: guochuyicmri <guochuyi@chinamobile.com>
    
1 file changed