When the device has only Ethernet ports, don't try to allocate range
of steerable UD QPs since they aren't needed.  This fixes an issue
where mlx4 VFs tried to allocate a range of UD steerable QPs, but
failed to do so.

Fixes: c1c98501 ("IB/mlx4: Add support for steerable IB UD QPs")
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>