net: dsa: mv8e6xxx: Fix stub function parameters

commit 64a26007a8f51442a9efddf7d98d50e2ca4349cd upstream.

mv88e6xxx_g2_atu_stats_get() takes two parameters. Make the stub
function also take two, otherwise we get compile errors.

Fixes: c5f299d59261 ("net: dsa: mv88e6xxx: global1_atu: Add helper for get next")
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>