nl80211: Fix RTM NEW/DELLINK IFLA_IFNAME copy for maximum ifname length

nl80211: Fix RTM NEW/DELLINK IFLA_IFNAME copy for maximum ifname length

If the kernel rtm_newlink or rtm_dellink send the maximum length of
ifname (IFNAMSIZ), the event handlers in
wpa_driver_nl80211_event_rtm_addlink() and
wpa_driver_nl80211_event_rtm_dellink() did not copy the IFLA_IFNAME
value. Because the RTA_PAYLOAD (IFLA_IFNAME) length already includes the
NULL termination, that equals the IFNAMSIZ.

Fix the condition when IFNAME reach maximum size.

Signed-off-by: Ouden <Ouden.Biz@gmail.com>