Add the crypto engine as a child of the NPE.

Link: https://lore.kernel.org/r/20210605161007.3397216-1-linus.walleij@linaro.org
Cc: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>