IB/ipoib: Add readout of statistics using ethtool

IB/ipoib: Add readout of statistics using ethtool

Orabug: 21498734

IPoIB collects statistics of traffic including number of packets
sent/received, number of bytes transferred, and certain errors. This
patch makes these statistics available to be queried by ethtool.

Change-Id: Ic159815fe0cc08770cd4111ec1df117b7349c154
Signed-off-by: Hans Westgaard Ry <hans.westgaard.ry@oracle.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Tested-by: Yuval Shaia <yuval.shaia@oracle.com>
Acked-by: Ajaykumar Hotchandani <ajaykumar.hotchandani@oracle.com>