crypto: atmel-aes - Fix counter overflow in CTR mode

32 bit counter is not supported by neither of our AES IPs, all implement
a 16 bit block counter. Drop the 32 bit block counter logic.

Fixes: fcac8365 ("crypto: atmel-aes - fix the counter overflow in CTR mode")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>