tests: Make ap_track_sta_no_probe_resp more robust

tests: Make ap_track_sta_no_probe_resp more robust

Check whether the unexpected BSS entry is based on having received a
Beacon frame instead of Probe Response frame. While this test case is
using a huge beacon_int value, it is still possible for mac80211_hwsim
timing to work in a way that a Beacon frame is sent. That made this test
case fail in some rare cases. Fix this by ignoring the BSS entry if it
is based on Beacon frame instead of Probe Response frame.

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