app/testpmd: configure RSS without restart

app/testpmd: configure RSS without restart

The function cmd_config_rss_parsed() associated with the command
"port config rss all" required to first stop all ports, in order to
then entirely re-configure all ports with the new RSS hash computation
parameters.
Use now the new function rte_eth_dev_rss_hash_conf_update() that dynamically
only changes the RSS hash computation parameters of a port, without needing
to previously stop the port.

Signed-off-by: Ivan Boule <ivan.boule@6wind.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>