net: macb: Added some queue statistics

Added statistics per queue:
- qX_rx_packets
- qX_rx_bytes
- qX_rx_dropped
- qX_tx_packets
- qX_tx_bytes
- qX_tx_dropped

Signed-off-by: Rafal Ozieblo <rafalo@cadence.com>
Signed-off-by: David S. Miller <davem@davemloft.net>