reiserfsck: support `fsck -f -n`

Every other fsck util out there supports non-interactive forcing and this
change brings reiserfsck into line.

Signed-off-by: Roy Marples <roy@marples.name>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>