tests: Clear data from ongoing scan on reset()

tests: Clear data from ongoing scan on reset()

It was possible for the previous test case to leave unexpected BSS or
P2P peer table entries if a scan was in progress when the FLUSH command
was used. This could result in test failures, e.g., when running
discovery_dev_type_go followed by discovery_group_client where a P2P
peer was discovered on another channel at the end of the former test
case from a scan that was running durign the FLUSH operation that was
supposed to remove all P2P peers. This could result in
discovery_group_client failing due to dev[2] trying to send the
discoverability frame on incorrect channel (the one learned in the
previous test case) since discover_peer() skipped a new device
discovery. Fix this by running FLUSH operation again if a pending scan
operation is detected during the first FLUSH operation.

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