Add hack to get around "." delimiter problem with policing vifs.

Add hack to get around "." delimiter problem with policing vifs.

The vswitchd.conf format uses "." as a delimiter.  Unfortunately, vifs
use a "." in their name.  The port is specified as part of the key when
ingress policing is enabled, but the cfg parser balks at this.  For the
time-being, we check all valid ports to see if they have a policing
policy defined.  This is wasteful, but it works until we change the
delimiter.