wifi: iwlwifi: mvm: support enabling and disabling HW timestamping

Instead of enabling HW timestamping by default every time a station
is connected, disable it by default and enable it only upon request
for a specific station. HW timestamping can be enabled for only one
peer at a time.

Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230320122330.62b98fbf545b.I450c1017ada7900a71a63d879bb542a08e3166c8@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>