Add support to abort vendor scan

Add support to abort vendor scan

This commit enhances the existing implementation of abort scan to also
abort concurrent active vendor scans. This is achieved by passing the
the scan_cookie to the driver interface with the intention to abort
the specific scan request. This scan_cookie is returned from the driver
interface when the scan request is scheduled.

This scan_cookie is 0 if the scan is triggered through the upstream
cfg80211 interface. Thus, the scan_cookie is used to determine whether
to abort the cfg80211 or vendor scan request.

Also, the previous implementation of relying on scan_work/p2p_scan_work
for the active work to trigger the abort scan is enhanced to check for
the started state of either of these work operations. This should also
help to abort the concurrent active scan/p2p-scan operations.

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