crypto: atmel-sha204a - fix negated return value

Fix negated variable return value.

Fixes: e05ce444 ("crypto: atmel-sha204a - add reading from otp zone")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-crypto/34cd4179-090e-479d-b459-8d0d35dd327d@moroto.mountain/


Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>