bonding: add Speed/Duplex information to /proc/net/bonding/bond

Effect:
 Slave Interface: eth5
 MII Status: up
 Speed: 10000 Mbps
 Duplex: full
 Link Failure Count: 0
 Permanent HW addr: XX:XX:XX:XX:XX:XX
 Slave queue ID: 0

Signed-off-by: Krzysztof Piotr Oledzki <ole@ans.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>