crypto: Deduplicate le32_to_cpu_array() and cpu_to_le32_array()

Deduplicate le32_to_cpu_array() and cpu_to_le32_array() by moving them
to the generic header.

No functional change implied.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>