be2net: add speed reporting for 40G/KR interface

This patch adds speed reporting via ethtool for 40Gbps KR4 interface
on the Skyhawk-R chip.

Signed-off-by: Kalesh AP <kalesh.purayil@emulex.com>
Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>