Staging: rtl8192su: convert to net_device_ops

commit e3804cbebb67887879102925961d41b503f7fbe3 removed
COMPAT_NET_DEV_OPS so this change is needed to make rtl8192su
buildable again.

Loosely based on Alexander's patch for rtl8187se, untested.

Cc: Alexander Beregalov <a.beregalov@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>