tls: Pass rec instead of aead_req into tls_encrypt_done

The function tls_encrypt_done only uses aead_req to get ahold of
the tls_rec object.  So we could pass that in instead of aead_req
to simplify the code.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>