The current code does not return after successfully preparing the MDB
addition on every ports member of a multicast group. Fix this.
Fixes: a1a6b7ea7f2d ("net: dsa: add cross-chip multicast support") Reported-by: Egil Hjelmeland <privat@egil-hjelmeland.no> Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Signed-off-by: David S. Miller <davem@davemloft.net>