wifi: iwlwifi: mvm: fix cancel_delayed_work_sync() deadlock

Lockdep points out that we can deadlock here by calling
cancel_delayed_work_sync() because that might be already
running and gotten interrupted by the NAPI soft-IRQ.
Even just calling something that can sleep is wrong in
this context though.

Luckily, it doesn't even really matter since the things
we need to do are idempotent, so just drop the _sync().

Fixes: e5d153ec

 ("iwlwifi: mvm: fix CSA AP side")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230514120631.b1813c823b4d.I9d20cc06d24fa40b6774d3dd95ea5e2bf8dd015b@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>