totemconfig: fix autogen mcastaddr for ipv6-4

When UDP is used as a transport, the error would occur
"Multicast address family does not match bind address family"
because there is no ipv6 in /etc/hosts specified but using the
totem.ip_version: ipv6-4. because
the mcastaddr generated (if not specified) only according to
the totem.ip_version.

Solution is to use bindnetaddr (configured or generated from
nodelist) addr family.

Signed-off-by: yuan ren <yren@suse.com>
Reviewed-by: Jan Friesse <jfriesse@redhat.com>