nl80211: Indicate interface-down event only for the main netdev

nl80211: Indicate interface-down event only for the main netdev

RTM_NEWLINK event without IFF_UP were processed for all related
interfaces (including VLANs and bridge). While these events may need to
be processed for other purposes, they should not end up claiming that
the main interface has been disabled, so indicate
EVENT_INTERFACE_DISABLED only if the ifname matches the first BSS ifname
for the interface. In addition, fix some of the ifup/down checks from
if_indextoname() cases to actually use the resolved ifname (namebuf)
rather than hardcoding the first configured ifname to be used.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>