staging: wlan-ng: fix leaks on failure paths in prism2sta_probe_usb()

There are leaks of resources allocated by wlan_setup() and usb_dev refcnt
on failure paths in prism2sta_probe_usb().

The patch adds appropriate deallocations and removes invalid code
from hfa384x_corereset() failure handling.
unregister_wlandev() is wrong because it is not registered yet.
hfa384x_destroy() is just noop in init state.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/wlan-ng/prism2usb.c

···
 					   prism2_reset_holdtime,
 					   prism2_reset_settletime, 0);
 		if (result != 0) {
-			unregister_wlandev(wlandev);
-			hfa384x_destroy(hw);
 			result = -EIO;
 			dev_err(&interface->dev, "hfa384x_corereset() failed.\n");
-			goto failed;
+			goto failed_reset;
 		}
 	}
 
···
 	if (register_wlandev(wlandev) != 0) {
 		dev_err(&interface->dev, "register_wlandev() failed.\n");
 		result = -EIO;
-		goto failed;
+		goto failed_register;
 	}
 
 	goto done;
 
+failed_register:
+	usb_put_dev(dev);
+failed_reset:
+	wlan_unsetup(wlandev);
 failed:
 	kfree(wlandev);
 	kfree(hw);