ipmi/of: Don't use unavailable interfaces

If an IPMI controller is used by the firmware and as such marked with
a reserved status, we shouldn't use it.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/ipmi/ipmi_si_intf.c

@@ -2658,6 +2658,9 @@ static int ipmi_probe(struct platform_device *dev)
 	if (!match)
 		return -EINVAL;
 
+	if (!of_device_is_available(np))
+		return -EINVAL;
+
 	ret = of_address_to_resource(np, 0, &resource);
 	if (ret) {
 		dev_warn(&dev->dev, PFX "invalid address from OF\n");