virnetserver: Raise log level of max_clients related messages

virnetserver: Raise log level of max_clients related messages

We have these configuration knobs, like max_clients and
max_anonymous_clients. They limit the number of clients
connected.  Whenever the limit is reached, the daemon stops
accepting new ones and resumes if one of the connected clients
disconnects. If that's the case, a debug message is printed into
the logs. And when the daemon starts over to accept new clients
too. However, the problem is the messages have debug priority.
This may be unfortunate, because if the daemon stops accepting
new clients all of a sudden, and users don't have debug logs
enabled they have no idea what's going on. Raise the messages
level to INFO at least.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>