net: usb: pegasus: fix memory leak in update_eth_regs_async()

When asynchronously writing to the device registers and if usb_submit_urb()
fail, the code fail to release allocated to this point resources.

Fixes: 323b34963d11 ("drivers: net: usb: pegasus: fix control urb submission")
Signed-off-by: Petko Manolov <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/usb/pegasus.c

···
 			netif_device_detach(pegasus->net);
 		netif_err(pegasus, drv, pegasus->net,
 			  "%s returned %d\n", __func__, ret);
+		usb_free_urb(async_urb);
+		kfree(req);
 	}
 	return ret;
 }