cfg80211: Add TDLS event to allow drivers to request operations

The NL80211_CMD_TDLS_OPER command was previously used only for userspace
request for the kernel code to perform TDLS operations. However, there
are also cases where the driver may need to request operations from
userspace, e.g., when using security on the AP path. Add a new cfg80211
function for generating a TDLS operation event for drivers to request a
new link to be set up (NL80211_TDLS_SETUP) or an existing link to be
torn down (NL80211_TDLS_TEARDOWN). Drivers can optionally use these
events, e.g., based on noticing data traffic being sent to a peer
station that is seen with good signal strength.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>