TDLS: Fix add/set STA operation
Commit a9a1d0f08aaf7c96f40def0d7966399b89b2a7c0 added vht_capabilities
to struct hostapd_sta_add_params but forgot to update
wpa_supplicant_tdls_peer_addset() to initialize the variable to NULL.
This could result in uninitialized pointer being used in
driver_nl80211.c when adding a TDLS peer entry. Fix this by clearing the
hostapd_sta_add_params with memset.
Signed-hostap: Jouni Malinen <jouni@qca.qualcomm.com>