bridge: re-introduce 'fix parsing of MLDv2 reports'

commit bc8c20ac ("bridge: multicast: treat igmpv3 report with
INCLUDE and no sources as a leave") seems to have accidentally reverted
commit 47cc84ce ("bridge: fix parsing of MLDv2 reports"). This
commit brings back a change to br_ip6_multicast_mld2_report() where
parsing of MLDv2 reports stops when the first group is successfully
added to the MDB cache.

Fixes: bc8c20ac ("bridge: multicast: treat igmpv3 report with INCLUDE and no sources as a leave")
Signed-off-by: NDavide Caratti <dcaratti@redhat.com>
Acked-by: NNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Acked-by: NThadeu Lima de Souza Cascardo <cascardo@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/bridge/br_multicast.c

@@ -1138,7 +1138,7 @@ static int br_ip6_multicast_mld2_report(struct net_bridge *br,
 		} else {
 			err = br_ip6_multicast_add_group(br, port,
 							 &grec->grec_mca, vid);
-			if (!err)
+			if (err)
 				break;
 		}
 	}