lantiq: fix broadcast packets leaking on the wrong vlan on xrx200

The ethernet driver uses a port map override via special tag to control
the ports on which multicast packets are sent. This was added to work
around an issue in the switch that was occasionally leaking packets onto
the wrong vlan.
Unfortunately the change had some leftover lines that were overwrting
the port map with a list of all ports, thus always leaking packets onto
the wront vlan.

Fix this by only enabling the override with the VLAN port map and only
if a matching VLAN port map was actually found

Signed-off-by: Felix Fietkau <nbd@nbd.name>

target/linux/lantiq/patches-4.4/0025-NET-MIPS-lantiq-adds-xrx200-net.patch

@@ -209,7 +209,7 @@ Subject: [PATCH 25/36] NET: MIPS: lantiq: adds xrx200-net
 +};
 --- /dev/null
 +++ b/drivers/net/ethernet/lantiq_xrx200.c
-@@ -0,0 +1,1850 @@
+@@ -0,0 +1,1851 @@
 +/*
 + *   This program is free software; you can redistribute it and/or modify it
 + *   under the terms of the GNU General Public License version 2 as published
@@ -1262,6 +1262,7 @@ Subject: [PATCH 25/36] NET: MIPS: lantiq: adds xrx200-net
 +	struct xrx200_chan *ch;
 +	struct ltq_dma_desc *desc;
 +	u32 byte_offset;
++	u16 port_map = 0;
 +	int ret = NETDEV_TX_OK;
 +	int len;
 +#ifdef SW_ROUTING
@@ -1279,8 +1280,6 @@ Subject: [PATCH 25/36] NET: MIPS: lantiq: adds xrx200-net
 +
 +#ifdef SW_ROUTING
 +	if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
-+		u16 port_map = priv->port_map;
-+		special_tag |= PORT_MAP_SEL | PORT_MAP_EN;
 +		if (skb->protocol == htons(ETH_P_8021Q)) {
 +			u16 vid;
 +			int i;
@@ -1294,9 +1293,11 @@ Subject: [PATCH 25/36] NET: MIPS: lantiq: adds xrx200-net
 +				}
 +			}
 +		}
-+		special_tag |= port_map << PORT_MAP_SHIFT;
 +	}
-+	special_tag |= priv->port_map << PORT_MAP_SHIFT;
++	if (port_map) {
++		special_tag |= (port_map << PORT_MAP_SHIFT) |
++			       PORT_MAP_SEL | PORT_MAP_EN;
++	}
 +	if(priv->wan)
 +		special_tag |= (1 << DPID_SHIFT);
 +	if(skb_headroom(skb) < 4) {

target/linux/lantiq/patches-4.9/0025-NET-MIPS-lantiq-adds-xrx200-net.patch

@@ -209,7 +209,7 @@ Subject: [PATCH 25/36] NET: MIPS: lantiq: adds xrx200-net
 +};
 --- /dev/null
 +++ b/drivers/net/ethernet/lantiq_xrx200.c
-@@ -0,0 +1,1849 @@
+@@ -0,0 +1,1850 @@
 +/*
 + *   This program is free software; you can redistribute it and/or modify it
 + *   under the terms of the GNU General Public License version 2 as published
@@ -1262,6 +1262,7 @@ Subject: [PATCH 25/36] NET: MIPS: lantiq: adds xrx200-net
 +	struct xrx200_chan *ch;
 +	struct ltq_dma_desc *desc;
 +	u32 byte_offset;
++	u16 port_map = 0;
 +	int ret = NETDEV_TX_OK;
 +	int len;
 +#ifdef SW_ROUTING
@@ -1279,8 +1280,6 @@ Subject: [PATCH 25/36] NET: MIPS: lantiq: adds xrx200-net
 +
 +#ifdef SW_ROUTING
 +	if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
-+		u16 port_map = priv->port_map;
-+		special_tag |= PORT_MAP_SEL | PORT_MAP_EN;
 +		if (skb->protocol == htons(ETH_P_8021Q)) {
 +			u16 vid;
 +			int i;
@@ -1294,9 +1293,11 @@ Subject: [PATCH 25/36] NET: MIPS: lantiq: adds xrx200-net
 +				}
 +			}
 +		}
-+		special_tag |= port_map << PORT_MAP_SHIFT;
 +	}
-+	special_tag |= priv->port_map << PORT_MAP_SHIFT;
++	if (port_map) {
++		special_tag |= (port_map << PORT_MAP_SHIFT) |
++			       PORT_MAP_SEL | PORT_MAP_EN;
++	}
 +	if(priv->wan)
 +		special_tag |= (1 << DPID_SHIFT);
 +	if(skb_headroom(skb) < 4) {