net/mlx5_core: Enable flow steering support for the IB driver

When the driver is loaded, we create flow steering namespace
for kernel bypass with nine priorities and another namespace
for leftovers(in order to catch packets that weren't matched).
Verbs applications will use these priorities.
we found nine as a number that balances the requirements from the
user and retains performance.

The bypass namespace is used by verbs applications that want to bypass
the kernel networking stack. The leftovers namespace is used by verbs
applications and the sniffer in order to catch packets that weren't
handled by any preceding rules.

Signed-off-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Matan Barak <matanb@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>