xfsprogs: metadump: no need for local copy of name when obfuscating

xfsprogs: metadump: no need for local copy of name when obfuscating

The local "newname" buffer in obfuscate_name() is used to hold an
obfuscated name as it gets generated.  But it is always copied back
into the passed-in name buffer, so we might as well just use the
name buffer passed directly and avoid the copy.

Signed-off-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>