mcb: request_mem_region() returns NULL on error

The code here is checking for IS_ERR() when request_mem_region() only
returns NULL on error and never an ERR_PTR.

Signed-off-by: Dan Carpenter <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/mcb/mcb-pci.c

···
 
 	res = request_mem_region(priv->mapbase, CHAM_HEADER_SIZE,
 				 KBUILD_MODNAME);
-	if (IS_ERR(res)) {
+	if (!res) {
 		dev_err(&pdev->dev, "Failed to request PCI memory\n");
-		ret = PTR_ERR(res);
+		ret = -EBUSY;
 		goto out_disable;
 	}