atlatnic: enable Nbase-t speeds with base-t

When 2.5G is advertised, N-Base should be advertised against the T-base
caps. N5G is out of use in baseline code and driver should treat both 5G
and N5G (and also 2.5G and N2.5G) equally from user perspective.

Fixes: 5cfd54d7 ("net: atlantic: minimal A2 fw_ops")
Signed-off-by: Nikita Danilov <ndanilov@aquantia.com>
Signed-off-by: Sudarsana Reddy Kalluru <skalluru@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>