ixgbe: create E610 specific ethtool_ops structure

E610's implementation of various ethtool ops is different than
the ones corresponding to ixgbe legacy products. Therefore create
separate E610 ethtool_ops struct which will be filled out in the
forthcoming patches.

Add adequate ops struct basing on MAC type. This step requires
changing a bit the flow of probing by placing ixgbe_set_ethtool_ops
after hw.mac.type is assigned. So move the whole netdev assignment
block after hw.mac.type is known. This step doesn't have any additional
impact on probing sequence.

Suggested-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Bharath R <bharath.r@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>