crypto: artpec6 - Use request_complete helpers

Use the request_complete helpers instead of calling the completion
function directly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>