s390/pci: Delete an unnecessary check before the function call "pci_dev_put"

The pci_dev_put() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/pci/pci_event.c

@@ -145,8 +145,7 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
 	default:
 		break;
 	}
-	if (pdev)
-		pci_dev_put(pdev);
+	pci_dev_put(pdev);
 }
 
 void zpci_event_availability(void *data)