Update git submodules

Update git submodules

* Update docs/submodules/vswitchperf from branch 'master'
  - install: Fedora installation script update

    An update of the Fedora installation scripts for versions 24,25 and 26.

    Change-Id: Ib510d78f4040e1029bc68d2fa303a4c0a6357de3
    Signed-off-by: Richard Elias <richardx.elias@intel.com>
    Reviewed-by: Martin Klozik <martinx.klozik@intel.com>
    Reviewed-by: Al Morton <acmorton@att.com>
    Reviewed-by: Christian Trautman <ctrautma@redhat.com>
    Reviewed-by: Sridhar Rao <sridhar.rao@spirent.com>
    Reviewed-by: Trevor Cooper <trevor.cooper@intel.com>