ethtool: add suffix _u32 to legacy bitmap members of struct ethtool_keee

This is in preparation of using the existing names for linkmode
bitmaps.

Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>