wifi: mac80211: ibss: stop transmit when merging IBSS

wifi: mac80211: ibss: stop transmit when merging IBSS

We disable the carrier, but that doesn't immediately take
effect, and as such a concurrent transmit can go into the
driver while drv_leave_ibss() is happening and confuse it.
Synchronize to avoid that.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250102161730.83b58167e80e.I538751fbe1b4302d20f6ed80afb024bca6a2dbf5@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>