IB/mlx4: Fix info returned when querying IBoE ports

To issue a port query, use the QUERY_(Ethernet)_PORT command instead
of the MAD_IFC command, since MAD_IFC attempts to query the firmware
IB SMA, which is irrelevant for IBoE ports.

This allows us to handle both 10Gb/s and 40Gb/s rates (e.g in sysfs),
using QDR speed (10Gb/s) and width of 1X or 4X.

Signed-off-by: Dotan Barak <dotanb@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>