crypto: fips - simplify one-level sysctl registration for crypto_sysctl_table

There is no need to declare an extra tables to just create directory,
this can be easily be done with a prefix path with register_sysctl().

Simplify this registration.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>