rhel: Use correct default port for OVN SB database
Fix typo in OVN SB database TCP port number.
Fixes: commit ("rhel: Firewall service files for OVN.")
<short>ovn-central-firewall-service</short>
<description>Firewall service for ovn central</description>
<port protocol="tcp" port="6641"/>
- <port protocol="tcp" port="6442"/>
+ <port protocol="tcp" port="6642"/>
</service>
