ath10k: avoid to set WEP key for TDLS peer

TDLS peer do not need WEP key. Setting WEP key will lead
to TDLS setup failure. Add fix to avoid setting WEP key
for TDLS peer.

Signed-off-by: Yingying Tang <yintang@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>