crypto: nx - use of_property_read_u32()

use of_propert_read_u32() for reading int value,
it can help reducing number of variables used

Signed-off-by: Saurabh Sengar <saurabh.truth@gmail.com>
Acked-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>