crypto: img-hash - Fix img_hash_match unused warning

Mark the of_device_id table as maybe_unused.  This fixes a W=1 warning:

  drivers/crypto/img-hash.c:930:34: error: ‘img_hash_match’ 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/img-hash.c

@@ -927,7 +927,7 @@ static void img_hash_done_task(unsigned long data)
 	img_hash_finish_req(hdev->req, err);
 }
 
-static const struct of_device_id img_hash_match[] = {
+static const struct of_device_id img_hash_match[] __maybe_unused = {
 	{ .compatible = "img,hash-accelerator" },
 	{}
 };