lxc: move debug/error log when adding IP addresses to virNetDevIPAddrAdd

lxc: move debug/error log when adding IP addresses to virNetDevIPAddrAdd

It makes more sense to have the logging at the lower level so other
callers can share the goodness.

While removing so much stuff from / touching so many lines in
lxcContainerRenameAndEnableInterfaces() (which used to have this
debug/error logging), label names were changed and it was updated to
use the now-more-common method of initializing ret to -1 (failure),
then setting to 0 right before the cleanup label.