crypto: atmel-sha204a - Mark OF related data as maybe unused

The driver can be compile tested with !CONFIG_OF making certain data
unused:

  drivers/crypto/atmel-sha204a.c:129:34: error: ‘atmel_sha204a_dt_ids’ defined but not used [-Werror=unused-const-variable=]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/atmel-sha204a.c

@@ -126,7 +126,7 @@ static void atmel_sha204a_remove(struct i2c_client *client)
 	kfree((void *)i2c_priv->hwrng.priv);
 }
 
-static const struct of_device_id atmel_sha204a_dt_ids[] = {
+static const struct of_device_id atmel_sha204a_dt_ids[] __maybe_unused = {
 	{ .compatible = "atmel,atsha204", },
 	{ .compatible = "atmel,atsha204a", },
 	{ /* sentinel */ }