airo.c currently has MICSUPPORT enabled, which requires CONFIG_CRYPTO.  A
user reported a build failure which is due to the lack of a Kconfig
dependency.  See http://bugs.debian.org/344205.

This patch makes Kconfig enforce this dependency.
Signed-off-by: Ndann frazier <dannf@debian.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NJeff Garzik <jgarzik@pobox.com>