examples/ip_pipeline: fix RSS

examples/ip_pipeline: fix RSS

After adding RSS hash offload checks, flags that are not supported by
the current device result in RSS configuration failing as opposed to
unsupported flags being silently discarded. This fix is making sure
that only device supported flags are passed to RSS configuration.

Fixes: aa1a6d87f15d ("ethdev: force RSS offload rules again")

Signed-off-by: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
Acked-by: Fan Zhang <roy.fan.zhang@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Tested-by: Yuan Peng <yuan.peng@intel.com>