mlxsw: spectrum_flower: Do not stop at FLOW_ACTION_PRIORITY

The handler for FLOW_ACTION_PRIORITY ends by returning whatever the
lower-level function that it calls returns. If there are more actions lined
up after this action, those are never offloaded. Fix by only bailing out
when the called function returns an error.

Fixes: 463957e3 ("mlxsw: spectrum_flower: Offload FLOW_ACTION_PRIORITY")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>