rapidio: fix potential NULL pointer dereference

The change fixes improper check for a returned error value by
class_create() function, which on error returns ERR_PTR() value, thus the
original check always results in a dead code on error path.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rapidio/devices/rio_mport_cdev.c

@@ -2669,9 +2669,9 @@ static int __init mport_init(void)
 
 	/* Create device class needed by udev */
 	dev_class = class_create(THIS_MODULE, DRV_NAME);
-	if (!dev_class) {
+	if (IS_ERR(dev_class)) {
 		rmcd_error("Unable to create " DRV_NAME " class");
-		return -EINVAL;
+		return PTR_ERR(dev_class);
 	}
 
 	ret = alloc_chrdev_region(&dev_number, 0, RIO_MAX_MPORTS, DRV_NAME);