wifi: mac80211: move scan work to wiphy work

[ Upstream commit 20171251 ]

Move the scan work to wiphy work, which also simplifies
the way we handle the work vs. the scan configuration.

Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Stable-dep-of: eadfb547 ("wifi: mac80211: move sched-scan stop work to wiphy work")
Signed-off-by: Sasha Levin <sashal@kernel.org>