crypto: nx - Fix numerous sparse byte-order warnings

The nx driver started out its life as a BE-only driver.  However,
somewhere along the way LE support was partially added.  This never
seems to have been extended all the way but it does trigger numerous
warnings during build.

This patch fixes all those warnings, but it doesn't mean that the
driver will work on LE.

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