[multipath] cosmetical fix

[multipath] cosmetical fix

I'd like to ask some cosmetical fix in libmultipath.
In Redhat /etc/rc.sysinit calls /sbin/multipath -v 0 after modprobe
dm-multipath to catch the disks already attached.

Now it prints a small garbage on screen for every map, I think.
Actually every multipath -F; multipath/multipath -v 0 sequence does
that.

The reason is neither print_multipath_topology nor
snprint_multipath_topology initialize buff if verbosity is 0.

Maxim Kozover