MAINTAINERS: Add maintianer entry for crypto/s5p-sss

Add Krzysztof Kozlowski and Vladimir Zapolskiy as maintainers of s5p-sss
driver for handling reviews, testing and getting bug reports from the
users.

Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>