crypto: sl3516 - Add sl3516 crypto engine

The cortina/gemini SL3516 SoC has a crypto IP name either (crypto
engine/crypto acceleration engine in the datasheet).
It support many algorithms like [AES|DES|3DES][ECB|CBC], SHA1, MD5 and
some HMAC.

This patch adds the core files and support for ecb(aes) and the RNG.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>