net/mlx5e: Use new ethtool get/set link ksettings API

Use new get/set link ksettings and remove get/set settings legacy
callbacks.
This allows us to use bitmasks longer than 32 bit for supported and
advertised link modes and use modes that were previously not supported.

Signed-off-by: Gal Pressman <galp@mellanox.com>
CC: Ben Hutchings <bwh@kernel.org>
CC: David Decotigny <decot@googlers.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>