crypto: drbg - Put rng_alg methods in logical order

crypto: drbg - Put rng_alg methods in logical order

Put the DRBG implementation of the rng_alg methods in the order in which
they're called (cra_init => set_ent => seed => generate => cra_exit) so
that it's easier to understand the flow.

Also rename drbg_kcapi_random to drbg_kcapi_generate, and
drbg_kcapi_cleanup to drbg_kcapi_exit, so they match the method names.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>