app/testpmd: support RSS config in flow query

app/testpmd: support RSS config in flow query

This patch support RSS action in flow query.
It can display the RSS configuration of the specified rule.

For example:
we can create an RSS rule by command "flow create 0 ingress
pattern eth / ipv4 / tcp / end actions rss types ipv4-tcp
l3-src-only l4-dst-only end queues end func symmetric_toeplitz
 / end" and then query it "flow query 0 0 rss"
the log will be follow
RSS:
 queues: none
 function: symmetric_toeplitz
 types:
  ipv4-tcp
  l3-src-only
  l4-dst-only

Signed-off-by: Chenxu Di <chenxux.di@intel.com>
Acked-by: Qiming Yang <qiming.yang@intel.com>