wifi: mac80211: use wiphy_hrtimer_work for CAC timeout

wifi: mac80211: use wiphy_hrtimer_work for CAC timeout

Prior initiating communication in a DFS channel, there should be a
monitoring of RADAR in that channel for a minimum of 600 seconds if it
is a Weather RADAR channel and 60 seconds for other DFS channels. This
Channel Availability Check(CAC) is currently implemented by scheduling
a work item for execution with a delay equal to an appropriate timeout.
But this work item is observed to take more delay than specified
(4-5 seconds in regular DFS channels and 25-30 seconds in Weather RADAR
channels). Even though this delay is expected in case of delayed work
queue as there is no guarantee that the work will be scheduled exactly
after the specified delay, a delay of more than 20 seconds is too much
for the AP to be in non-operational state.

Recently commit 7ceba45a6658 ("wifi: cfg80211: add an hrtimer based
delayed work item") added an infrastructure to overcome this issue by
supporting high resolution timers for mac80211 delayed work, which do not
have this timeout latency. Switch the CAC timeout to use this
infrastructure, so the CAC completion handling is triggered with tighter
timing and reduced latency.

Signed-off-by: Amith A <amith.a@oss.qualcomm.com>
Link: https://patch.msgid.link/20260130035511.2328713-1-amith.a@oss.qualcomm.com
[fix delay handling]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>