[CRYPTO] khazad: Use 32-bit reads on key

On 64-bit platform, reading 64-bit keys (which is supposed to be
32-bit aligned) at a time will result in unaligned access.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>