mlx4_core: Add support for steerable IB UD QPs

This patch adds support for allocating IB UD QPs that we can steer
traffic from.  We introduce a new firmware command FLOW_STEERING_IB_UC_QP_RANGE
and a capability bit.

This command isn't supported for VFs.

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