iw: use correct type in policy check for mesh

iw: use correct type in policy check for mesh

NL80211_STA_INFO_CONNECTED_TO_AS and NL80211_STA_INFO_CONNECTED_TO_GATE
are defined as u8 in kernel, but were checked against NLA_FLAG.

This fixes:

root@openwrt:~# iw dev wlan0-mesh station
failed to parse nested attributes!
failed to parse nested attributes!
failed to parse nested attributes!

Reported-by: Marc Rantanen <marc@eciceron.se>
Tested-by: Marc Rantanen <marc@eciceron.se>
Signed-off-by: Markus Theil <markus.theil@tu-ilmenau.de>
Link: https://lore.kernel.org/r/20201205092615.131561-1-markus.theil@tu-ilmenau.de
Signed-off-by: Johannes Berg <johannes.berg@intel.com>