wifi: mac80211: cancel TTLM teardown work earlier

It shouldn't be possible to run this after disconnecting, so
cancel the work earlier.

Fixes: a17a58ad ("wifi: mac80211: add support for tearing down negotiated TTLM")
Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240506211034.096a10ccebec.I5584a21c27eb9b3e87b9e26380b627114b32ccba@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>