ath10k: block offchannel operations if TDLS session is active

Do not allow off channel operations like scans/roc when
there are active TDLS sessions.

The Current firmware 10.4-3.5.1-00035 on QCA9888 does not
supports any offchannel operations on active TDLS sessions,
either driver needs to block the offchannel operation requests
or should teardown the TDLS connection.

Signed-off-by: Anilkumar Kolli <akolli@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>