crypto: algif_skcipher - Remove custom release parent function

commit d7b65aee upstream.

This patch removes the custom release parent function as the
generic af_alg_release_parent now works for nokey sockets too.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>