wifi: iwlwifi: mvm: read synced time from firmware if supported

wifi: iwlwifi: mvm: read synced time from firmware if supported

If the firmware supports reading synced GP2/ATRB timestamps,
read the synced timestamps from firmware instead of reading the
GP2 register and the system time separately. Reading the synced
time from firmware should be more accurate.

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.a6be5f0b5580.Idedb496a5943fa496143066ffbed08185a8c4582@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>