hwrng: bcm2835 - fix probe as platform device

BCM63XX (MIPS) does not use device tree, so there cannot be any
of_device_id, causing the driver to fail on probe:

[    0.904564] bcm2835-rng: probe of bcm63xx-rng failed with error -22

Fix this by checking for match data only if we are probing from device
tree.

Fixes: 8705f24 ("hwrng: bcm2835 - Enable BCM2835 RNG to work on BCM63xx platforms")
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/bcm2835-rng.c

@@ -168,14 +168,16 @@ static int bcm2835_rng_probe(struct platform_device *pdev)
 	priv->rng.read = bcm2835_rng_read;
 	priv->rng.cleanup = bcm2835_rng_cleanup;
 
-	rng_id = of_match_node(bcm2835_rng_of_match, np);
-	if (!rng_id)
-		return -EINVAL;
-
-	/* Check for rng init function, execute it */
-	of_data = rng_id->data;
-	if (of_data)
-		priv->mask_interrupts = of_data->mask_interrupts;
+	if (dev_of_node(dev)) {
+		rng_id = of_match_node(bcm2835_rng_of_match, np);
+		if (!rng_id)
+			return -EINVAL;
+
+		/* Check for rng init function, execute it */
+		of_data = rng_id->data;
+		if (of_data)
+			priv->mask_interrupts = of_data->mask_interrupts;
+	}
 
 	/* register driver */
 	err = devm_hwrng_register(dev, &priv->rng);