rhel: Change service providers to 'openvswitch'.

In Red Hat, the service name is "openvswitch", providers also should
be change to "openvswitch"

Signed-off-by: Dongdong <dongdong1@huawei.com>
Acked-by: Chunhe Li <lichunhe@huawei.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>