sfc: fix flow type handling for RSS filters

The FLOW_RSS flag was causing us to insert UDP filters when TCP was wanted.

Fixes: 42356d9a ("sfc: support RSS spreading of ethtool ntuple filters")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>