net/bonding: do not ignore RSS key on device config

net/bonding: do not ignore RSS key on device config

Bonding driver ignores the value of RSS key (that is set in the port RSS
configuration) in bond_ethdev_configure(). So the only way to set
non-default RSS key is by using rss_hash_update(). This is not an
expected behaviour.

Make the bond_ethdev_configure() set default RSS key only if
requested key is set to NULL.

Fixes: 734ce47f71e0 ("bonding: support RSS dynamic configuration")
Cc: stable@dpdk.org
Signed-off-by: Igor Romanov <igor.romanov@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>
Acked-by: Chas Williams <chas3@att.com>