usb: fix improper return value when kzalloc fails

The comment says function wa_nep_queue() should return 0 if ok, and <0
errno code on error. However, its implementation always returns 0, even
if the call to kzalloc() fails. As a result, the return value may be
inconsistent with the execution status, which may mislead the callers.
This patch fixes the bug, returning -ENOMEM when the call to kzalloc()
fails.
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/wusbcore/wa-nep.c

@@ -198,6 +198,7 @@ static int wa_nep_queue(struct wahc *wa, size_t size)
 	if (nw == NULL) {
 		if (printk_ratelimit())
 			dev_err(dev, "No memory to queue notification\n");
+		result = -ENOMEM;
 		goto out;
 	}
 	INIT_WORK(&nw->work, wa_notif_dispatch);