Initialize wireless interface attributes in proper function

Initialize wireless interface attributes in proper function

Currently multicast to unicast feature may be configured for incorrect wireless interface in case of reconfiguration.

Test case:

Initial wireless configuration:

config wifi-iface
  option mode ap
  option disabled 1

config wifi-iface
  option mode sta
  option disabled 0

config wifi-iface
  option mode ap
  option disabled 0

After reboot, multicast to unicast feature is configured for interface #3 (wlan0-1) only.

Next, enable interface #1 and issue "wifi" command. Now, multicast to unicast feature is configured for interface #2 (wlan0) which is wrong.
It should be configured for interfaces #1 and #3 only. This patch resolves this problem.

Signed-off-by: Dmitry Ivanov <dima@ubnt.com>
Signed-off-by: Felix Fietkau <nbd@openwrt.org>