crypto: ixp4xx - Hardware crypto support for IXP4xx CPUs

Add support for the hardware crypto engine provided by the NPE C
of the Intel IXP4xx networking processor series.

Supported ciphers: des, des3, aes
and a combination of them with md5 and sha1 hmac

Signed-off-by: Christian Hohnstaedt <chohnstaedt@innominate.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>