Currently it takes an error code as status, but what we really want to
tell is if the scan was aborted or not.

Also fix a bug where we were comparing firmware scan status values
with kernel error codes, which is obviously wrong. This meant
that ath6kl didn't detect when firmware informed about failed scans. I
doubt that this fix doesn't make any difference in practise but it
still needs to be fixed. This is fixed by adding an enum for the success
status code and checking for that.
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>