crypto: brcm - Add Broadcom SPU driver

Add Broadcom Secure Processing Unit (SPU) crypto driver for SPU
hardware crypto offload. The driver supports ablkcipher, ahash,
and aead symmetric crypto operations.

Signed-off-by: Steve Lin <steven.lin1@broadcom.com>
Signed-off-by: Rob Rice <rob.rice@broadcom.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>