crypto: rng - Mark crypto_rng_reset seed as const

crypto: rng - Mark crypto_rng_reset seed as const

Orabug: 26330509

There is no reason why crypto_rng_reset should modify the seed
so this patch marks it as const.  Since our algorithms don't
export a const seed function yet we have to go through some
contortions for now.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
(cherry picked from commit 3c5d8fa9f56ad0928e7a1f06003e5034f5eedb52)
Signed-off-by: Somasundaram Krishnasamy <somasundaram.krishnasamy@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>