volscan: fix copyright and licence notice

These are new files and new content; fix the copyright notice and
license to reflect.

Change-Id: I8d5f00fb7edaf2e3855e2dc2a1af07bba471c0d6
Reviewed-on: http://gerrit.openafs.org/11362
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>