[PATCH] unusual_devs update for UCR-61S2B

The existing unusual_devs entry for the UCR-61S2B appears to have too
wide a revision range.  It matches at least one device that doesn't
respond to the initialization sequence.  Perhaps the sequence needs to
be updated, or perhaps something else can be done.  For now, this patch
(as764) restricts the range to include only the revision mentioned in
the original comment.

This resolves (for now!) Bugzilla entry #6950.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>