tests: Make ap_hs20_session_info more robust

tests: Make ap_hs20_session_info more robust

It looks like mac80211 scan-while-associated can now take over 10
seconds with the current wireless-regdb rules for world roaming due to
number of additional DFS channel having been enabled for passive
scanning. This resulted in ap_hs20_session_info failing due to the wait
for the scan result event timing out. That is not really a real failure,
so increase the timeout to avoid reporting this incorrectly.

Signed-off-by: Jouni Malinen <j@w1.fi>