net: libwx: Configure Rx and Tx unit on hardware

Configure hardware for preparing to process packets. Including configure
receive and transmit unit of the MAC layer, and setup the specific rings.

Signed-off-by: Jiawen Wu <jiawenwu@trustnetic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Jiawen Wu