cryptocheck: Support multiple IV sizes for AES-CCM.

By default, the "normal" IV size (12) is used, but it can be overriden
via -I. If -I is not specified and -z is specified, issue requests
for all possible IV sizes.

Reviewed by: markj
Sponsored by: Chelsio Communications, The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D32110