crypto: rng - Introduce crypto_rng_generate

crypto: rng - Introduce crypto_rng_generate

Orabug: 26330509

This patch adds the new top-level function crypto_rng_generate
which generates random numbers with additional input.  It also
extends the mid-level rng_gen_random function to take additional
data as input.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
(cherry picked from commit ff030b099a21a4753af575b4304249e88400e506)
Signed-off-by: Somasundaram Krishnasamy <somasundaram.krishnasamy@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>