Allow watch(8) to use more than 10 snp* devices. This limitation was purely
due to the way watch(8) looks for available snoop devices.

PR: bin/118286
Submitted by: Mykola Zubach <zuborg@advancedhosters.com>
Reviewed by: rwatson, csjp, imp (all a long time ago)
Approved by: imp (mentor) (long time ago)
MFC after: 1 week