crypto: rng - Fix a refcounting bug in crypto_rng_reset()

We need to decrement this refcounter on these error paths.

Fixes: f7d76e05 ("crypto: user - fix use_after_free of struct xxx_request")
Cc: <stable@vger.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>