net: ethernet: ti: ale: fix seeing unreg mcast packets with promisc and allmulti disabled

On AM65xx MCU CPSW2G NUSS and 66AK2E/L NUSS the unregistered multicast
packets are still can be received with promisc and allmulti disabled.

This happens, because ALE VLAN entries on these SoCs do not contain port
masks for reg/unreg mcast packets, but instead store indexes of
ALE_VLAN_MASK_MUXx_REG registers which intended for store port masks for
reg/unreg mcast packets.

ALE VLAN entry:UNREG_MCAST_FLOOD_INDEX -> ALE_VLAN_MASK_MUXx
ALE VLAN entry:REG_MCAST_FLOOD_INDEX -> ALE_VLAN_MASK_MUXy

The commit b361da83 ("net: netcp: ale: add proper ale entry mask bits
for netcp switch ALE") update ALE code to support such ALE entries, it is
always used ALE_VLAN_MASK_MUX0_REG index in ALE VLAN entry for unreg mcast
packets mask configuration, which is read-only, at least for AM65xx MCU
CPSW2G NUSS and 66AK2E/L NUSS. As result unreg mcast packets are allowed
always.

Hence, update ALE code to use ALE_VLAN_MASK_MUX1_REG index for ALE VLAN
entries to configure unreg mcast port mask.

Fixes: b361da83

 ("net: netcp: ale: add proper ale entry mask bits for netcp switch ALE")
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Tested-by: Murali Karicheri <m-karicheri2@ti.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>