net/failsafe: fix sub-device ownership race

net/failsafe: fix sub-device ownership race

There is time between the sub-device port probing by the sub-device PMD
to the sub-device port ownership taking by a fail-safe port.

In this time, the port is available for the application usage. For
example, the port will be exposed to the applications which use
RTE_ETH_FOREACH_DEV iterator.

Thus, ownership unaware applications may manage the port in this time
what may cause a lot of problematic behaviors in the fail-safe
sub-device initialization.

Register to the ethdev NEW event to take the sub-device port ownership
before it becomes exposed to the application.

Fixes: a46f8d584eb8 ("net/failsafe: add fail-safe PMD")
Cc: stable@dpdk.org
Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Gaetan Rivet <gaetan.rivet@6wind.com>
Reviewed-by: Stephen Hemminger <stephen@networkplumber.org>