hwrng: optee - handle unlimited data rates

Data rates of MAX_UINT32 will schedule an unnecessary one jiffy
timeout on the call to msleep. Avoid this scenario by using 0 as the
unlimited data rate.
Signed-off-by: NJorge Ramirez-Ortiz <jorge@foundries.io>
Reviewed-by: NSumit Garg <sumit.garg@linaro.org>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/optee-rng.c

@@ -128,7 +128,7 @@ static int optee_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
 		data += rng_size;
 		read += rng_size;
 
-		if (wait) {
+		if (wait && pvt_data->data_rate) {
 			if (timeout-- == 0)
 				return read;
 			msleep((1000 * (max - read)) / pvt_data->data_rate);