crypto: atmel - Remove possible typo error

Commit bd3c7b5c ("crypto: atmel - add Atmel AES driver") possibly
has a typo error of adding an extra CONFIG_.

CC: Nicolas Royer <nicolas@eukrea.com>
Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>