drivers/s390/char/monreader.c: fix error return code

Convert a nonnegative error return code to a negative one, as returned
elsewhere in the function.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
(
if@p1 (\(ret < 0\|ret != 0\))
 { ... return ret; }
|
ret@p1 = 0
)
... when != ret = e1
    when != &ret
*if(...)
{
  ... when != ret = e2
      when forall
 return ret;
}
// </smpl>

Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/char/monreader.c

@@ -571,8 +571,11 @@ static int __init mon_init(void)
 	if (rc)
 		goto out_iucv;
 	monreader_device = kzalloc(sizeof(struct device), GFP_KERNEL);
-	if (!monreader_device)
+	if (!monreader_device) {
+		rc = -ENOMEM;
 		goto out_driver;
+	}
+
 	dev_set_name(monreader_device, "monreader-dev");
 	monreader_device->bus = &iucv_bus;
 	monreader_device->parent = iucv_root;