app/testpmd: fix RSS flow action configuration

app/testpmd: fix RSS flow action configuration

Except for a list of queues, RSS configuration (hash key and fields) cannot
be specified from the flow command line and testpmd does not provide safe
defaults either.

In order to validate their implementation with testpmd, PMDs had to
interpret its NULL RSS configuration parameters somehow, however this has
never been valid to begin with.

This patch makes testpmd always provide default values.

The list of RSS types to use is exclusively taken from the global "rss_hf"
variable, itself configured through the "port config all rss" command or
--rss-ip/--rss-udp command-line options.

Fixes: 05d34c6e9d2c ("app/testpmd: add queue actions to flow command")
Cc: stable@dpdk.org
Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
Acked-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>