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 <khoroshilov@ispras.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>