crypto: hisilicon/trng - fix local variable type

The return value of 'readl_poll_timeout' is '0' or '-ETIMEDOUT'. Therefore,
change the local variable 'ret' type from 'u32' to 'int'.
Signed-off-by: Weili Qian <qianweili@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/hisilicon/trng/trng.c

@@ -185,7 +185,7 @@ static int hisi_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
 	struct hisi_trng *trng;
 	int currsize = 0;
 	u32 val = 0;
-	u32 ret;
+	int ret;
 
 	trng = container_of(rng, struct hisi_trng, rng);