jsonrpc: Wrong key name for getDevicesVisibility


Bug-Url: https://bugzilla.redhat.com/1159637
Change-Id: I63180a87e40e48134e6da8b9996f849362fb5501
Signed-off-by: pkliczewski <piotr.kliczewski@gmail.com>
Reviewed-on: http://gerrit.ovirt.org/35014
Reviewed-by: Allon Mureinik <amureini@redhat.com>
Tested-by: Maor Lipchuk <mlipchuk@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>