qede: Add basic ethtool support

This adds basic ethtool operations to the qed driver, allowing support in:
 - Statistics gathering [ethtool -S]
 - Setting of debug level [ethtool -s <interface> msglvl]
 - Getting basic information [ethtool, ethtool -i]

In addition it adds the ability to change the MTU.

Signed-off-by: Sudarsana Kalluru <Sudarsana.Kalluru@qlogic.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>