devlink: Pass extack when setting trap's action and group's parameters

A later patch will refuse to set the action of certain traps in mlxsw
and also to change the policer binding of certain groups. Pass extack so
that failure could be communicated clearly to user space.

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