ath6kl: add ath6kl_ prefix to crypto_type

Prevent a namespace conflict as in following patches as skbuff.h will
include the crypto API.

Acked-by: David S. Miller <davem@davemloft.net>
Cc: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sagi Grimberg <sagi@lightbitslabs.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>