lxc: Create a separate method to handle IPv{4, 6} outside parser

lxc: Create a separate method to handle IPv{4, 6} outside parser

The new method called lxcNetworkParseDataIPs() is responsible to handle
IPv{4,6} settings now. The idea is let lxcNetworkWalkCallback() method
handle all entries related to network definition only.

Signed-off-by: Julio Faracco <jcfaracco@gmail.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>