crypto: atmel-aes - Fix saving of IV for CTR mode

The req->iv of the skcipher_request is expected to contain the
last used IV. Update the req->iv for CTR mode.

Fixes: bd3c7b5c ("crypto: atmel - add Atmel AES driver")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>