qede: Add ethtool support for Energy efficient ethernet.

The patch adds ethtool callback implementations for querying/configuring
the Energy Efficient Ethernet (EEE) parameters.

Signed-off-by: Sudarsana Reddy Kalluru <Sudarsana.Kalluru@cavium.com>
Signed-off-by: Yuval Mintz <yuval.mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>