iwlwifi: mvm: implement mac80211 TDLS channel-switch APIs

Maintain a TDLS channel-switch state and update it according to
notifications from FW and timeouts. Explicitly check all state
transitions are valid.
When switching is initiated by mac80211, use a delayed work to
periodically reschedule it from iwlwifi.
Give the FW mac80211 generated TDLS channel-switch request/response
templates. It will change appropriate values (switch timings) and Tx
them at appropriate times.

Enable the channel switch wiphy capability bit when the FW supports it.

Signed-off-by: Arik Nemtsov <arikx.nemtsov@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>