USB: usbmon: drop Kconfig defaults

These statements seem to be unnecessary. No idea why, but I built all
possible configurations and everything gets built just as before.

It's an old patch that popped from discussion with Paul in November 2008.
Obviously not a very high priority but better late than never.

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>