MAINTAINERS: add gemini crypto sl3516-ce

Add myself as maintainer of gemini sl3516-ce crypto driver.
Add also the driver to the list of files for gemini SoC.

Reviewed-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>