ath6kl: Replace internal node table with cfg80211 BSS table

The internal node table in ath6kl was not really used for any useful
purpose. It was just used to collect scan results during a scan and then
provide them in a burst to cfg80211 at the completion of the scan. There
is no point in doing this since cfg80211 is perfectly capable of
maintaining the BSS table and the BSS inform messages are sent in
separate function calls anyway.

This provides more complete information in the cfg80211 BSS table since
this allows Beacon and Probe Response frames to be distinguished and IEs
from them reported separately.

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