ice: ethtool: advertise 1000M speeds properly

In current implementation ice_update_phy_type enables all link modes
for selected speed. This approach doesn't work for 1000M speeds,
because both copper (1000baseT) and optical (1000baseX) standards
cannot be enabled at once.

Fix this, by adding the function `ice_set_phy_type_from_speed()`
for 1000M speeds.

Fixes: 48cb27f2 ("ice: Implement handlers for ethtool PHY/link operations")
Signed-off-by: Anatolii Gerasymenko <anatolii.gerasymenko@intel.com>
Tested-by: Gurucharan <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>