IB/mlx5: Rename RoCE related helpers to reflect being Eth ones

This is a pre-step towards having mlx5 IB device also over Eth ports where
RoCE is not supported. We change the roce enable/disable and roce_lag
init/fini function names to have _eth instead of _roce.

This patch doesn't change any functionality.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>