mlxsw: spectrum_router: Configure RIFs based on RIF struct

All the information necessary for the configuration of RIFs can now be
found in the RIF struct itself, so reduce the arguments list.

This gets us one step closer to the common RIF core.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>