net: ethernet: ixgbe: Convert EEE to use linkmodes

Convert the tables to make use of ETHTOOL link mode bits, rather than
the old u32 SUPPORTED speeds. Make use of the linkmode helps to set
bits and compare linkmodes. As a result, the _u32 members of keee are
no longer used, a step towards removing them.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>